Commonwealth v. Gerhardt , 477 Mass. 775 ( 2017 )


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    SJC-11967
    COMMONWEALTH   vs.   THOMAS J. GERHARDT.
    Worcester.    January 6, 2017. - September 19, 2017.
    Present:     Gants, C.J., Lenk, Hines, Gaziano, Lowy, & Budd, JJ.1
    Marijuana. Motor Vehicle, Operating under the influence.
    Evidence, Field sobriety test.
    Complaint received and sworn to in the Worcester Division
    of the District Court Department on April 24, 2013.
    A motion for a hearing to challenge the admissibility of
    certain evidence was heard by Andrew M. D'Angelo, J., and
    questions of law were reported by him to the Appeals Court.
    The Supreme Judicial Court granted an application for
    direct appellate review.
    Rebecca A. Jacobstein, Committee for Public Counsel
    Services, for the defendant.
    Michelle R. King, Assistant District Attorney, for the
    Commonwealth.
    Steven S. Epstein & Marvin Cable, for National Organization
    for the Reform of Marijuana Laws, amicus curiae, submitted a
    brief.
    Michael A. Delsignore & Julie Gaudreau, for National
    College for DUI Defense, amicus curiae, submitted a brief.
    1
    Justice Hines participated in the deliberation on this
    case prior to her retirement.
    2
    GAZIANO, J.   In this case we are asked to consider the
    admissibility of field sobriety tests (FSTs) where a police
    officer suspects that a driver has been operating under the
    influence of marijuana.     Police typically administer three
    FSTs -- the "horizontal gaze nystagmus test," the "walk and turn
    test" and the "one leg stand test" -- during a motor vehicle
    stop in order to assess motorists suspected of operating under
    the influence of alcohol or other drugs.     These tests were
    developed specifically to measure alcohol consumption, and there
    is wide-spread scientific agreement on the existence of a strong
    correlation between unsatisfactory performance and a blood
    alcohol level of at least .08%.
    By contrast, in considering whether a driver is operating
    under the influence of marijuana, there is as yet no scientific
    agreement on whether, and, if so, to what extent, these types of
    tests are indicative of marijuana intoxication.     The research on
    the efficacy of FSTs to measure marijuana impairment has
    produced highly disparate results.     Some studies have shown no
    correlation between inadequate performance on FSTs and the
    consumption of marijuana; other studies have shown some
    correlation with certain FSTs, but not with others; and yet
    other studies have shown a correlation with all of the most
    frequently used FSTs.     In addition, other research indicates
    3
    that less frequently used FSTs in the context of alcohol
    consumption may be better measures of marijuana intoxication.
    The lack of scientific consensus regarding the use of
    standard FSTs in attempting to evaluate marijuana intoxication
    does not mean, however, that FSTs have no probative value beyond
    alcohol intoxication.    We conclude that, to the extent that they
    are relevant to establish a driver's balance, coordination,
    mental acuity, and other skills required to safely operate a
    motor vehicle, FSTs are admissible at trial as observations of
    the police officer conducting the assessment.     The introduction
    in evidence of the officer's observations of what will be
    described as "roadside assessments" shall be without any
    statement as to whether the driver's performance would have been
    deemed a "pass" or a "fail," or whether the performance
    indicated impairment.    Because the effects of marijuana may vary
    greatly from one individual to another, and those effects are as
    yet not commonly known, neither a police officer nor a lay
    witness who has not been qualified as an expert may offer an
    opinion as to whether a driver was under the influence of
    marijuana.2
    1.   Background.   a.   Prior proceedings.   Following a motor
    vehicle stop, Thomas Gerhardt was charged in the District Court
    2
    We acknowledge the amicus briefs in support of the
    defendant submitted by the National College for DUI Defense and
    the National Organization for the Reform of Marijuana Laws.
    4
    with operating a motor vehicle under the influence of marijuana,
    in violation of G. L. c. 90, § 24.     Gerhardt filed a motion for
    a Daubert-Lanigan hearing, seeking to challenge the
    admissibility of evidence concerning his performance on FSTs
    conducted after the stop.     See Daubert v. Merrell Dow Pharms.,
    Inc., 
    509 U.S. 579
    , 592-595 (1993); Commonwealth v. Lanigan, 
    419 Mass. 15
    , 24-27 (1994).     After an evidentiary hearing, a
    District Court judge reported four questions to the Appeals
    Court, pursuant to Mass. R. Crim. P. 34, as amended, 
    442 Mass. 1501
     (2004).
    "1. Whether police officers may testify to the
    administration and results of standard [FSTs] in
    prosecutions for [o]perating [u]nder the [i]nfluence of
    [m]arijuana as they do in [o]perating [u]nder the
    [i]nfluence of [a]lcohol prosecutions?
    "2. Are the effects of marijuana consumption
    sufficiently within the common knowledge and experience of
    a lay person, such that a non-expert witness may offer
    opinion evidence whether a person is 'high' on marijuana?
    "3. May a police officer, who has not been qualified
    as an expert witness, testify to the effects of marijuana
    on a person such as bloodshot eyes, lack of coordination
    and/or balance, reaction times, slow speech, paranoia, or
    relaxed responses[?]
    "4. May a juror rely on their own experience and
    common sense about the effects of marijuana as they may do
    in an [o]perating [u]nder the [i]nfluence of [a]lcohol
    prosecution?" [footnote omitted].
    We granted Gerhardt's application for direct appellate
    review.   After oral argument, we remanded the matter to the
    District Court judge who had reported the questions for further
    5
    findings on eleven specific issues.       Following the return of the
    judge's findings, we again heard oral argument in the matter.
    b.    Facts.    The parties submitted a statement of agreed
    facts as to the evidence that the Commonwealth would seek to
    present at trial.       On February 13, 2013, at approximately
    12:20 A.M., Trooper French of the State police3 observed a blue
    Suzuki Grand Vitara motor vehicle traveling south on Route 146,
    without the rear lights on.       French followed the vehicle as it
    left Route 146 at exit 8.       He activated his emergency lights and
    stopped the vehicle on Elmwood Street in Millbury.
    French approached the vehicle on the passenger side.        There
    were three occupants in the vehicle:       the driver, later learned
    to be Gerhardt, and two passengers.       French saw smoke inside the
    vehicle, and, as soon as the front passenger window was lowered,
    he detected "the distinct odor of burnt marijuana."       He also saw
    a large amount of what he identified as cigar tobacco on the
    floor, and a cigar slicer on the key ring in the ignition.       The
    trooper asked the driver for his driver's license and
    registration.       Gerhardt handed him the license and said that he
    did not have his registration.
    French asked Gerhardt how much marijuana was in the
    vehicle.    Gerhardt responded that there were "a couple of
    roaches" in the ashtray; he pulled two largely-consumed rolled
    3
    Trooper French's first name is not apparent in the record.
    6
    cigarettes from the ashtray and handed them to French.     French
    then asked when the occupants had smoked marijuana.    One of the
    passengers responded that they had smoked about twenty minutes
    previously.    Gerhardt said that it had been about three hours
    earlier.   French walked to the driver's side of the vehicle and
    noticed that the light switch was in the "off" position.     He
    asked Gerhardt how much he had smoked.    Gerhardt responded that
    he had smoked approximately one gram of marijuana.
    French then asked Gerhardt to step out of the vehicle to
    perform FSTs.    French administered a number of FSTs, including
    the horizontal gaze nystagmus test (HGN);4 the nine-step walk-
    and-turn test (WAT); and the one-leg-stand test (OLS).     French
    also asked Gerhardt to recite the alphabet from D to Q and to
    count backward from seventy-five to sixty-two.
    Gerhardt had no nystagmus indicators, and was able to
    recite the requested portion of the alphabet and to count
    backwards.    He did not perform the WAT as instructed, even after
    4
    "Nystagmus is '[a]n abnormal and involuntary movement of
    the eyeballs from side to side or up and down, but usually from
    side to side.'" Commonwealth v. Sands, 
    424 Mass. 184
    , 186
    (1997), quoting State v. Merritt, 
    36 Conn. App. 76
    , 84 (1994).
    An officer administers the HGN test by having the subject focus
    on a moving object and observing whether the subject is able to
    follow the object smoothly with his or her eyes, whether the
    subject's eyes bounce at the extremes of the field of vision,
    and whether they exhibit nystagmus, where there is an angle of
    less than forty-five degrees between the eyes and the object.
    Sands, supra at 186-187. Introduction of the results of this
    test at trial requires expert testimony. See id. at 188.
    7
    several explanations and a demonstration by the trooper in
    response to Gerhardt's first answer in the negative when asked
    whether he understood the instructions.     Rather than standing
    heel to toe, with his right foot in front and his left toes
    touching his heel, as he had been shown, Gerhardt moved his feet
    so that they were side by side; he also did not turn around as
    instructed.   French determined that "the results of this test
    indicated that Gerhardt was impaired."    The trooper then
    provided instructions and gave a demonstration of the OLS test,
    and Gerhard indicated that he understood.     In performing the
    test, however, Gerhard did not remain upright on one foot,
    instead putting his foot down multiple times, and swayed.
    French determined that "the results of this test indicated that
    Gerhardt was impaired."
    After administering these tests, French concluded that
    Gerhardt was under the influence of marijuana.     French informed
    Gerhardt that he was not under arrest, but had him sit in the
    back of French's cruiser.   Both passengers were asked to step
    out of the vehicle and were pat frisked.     They, too, were told
    that they were not under arrest, and were placed in the back
    seat of the cruiser.   A second trooper arrived at the scene.
    During a search of the vehicle, the troopers recovered two more
    marijuana "roaches" and a marijuana stem.
    8
    On April 24, 2013, a criminal complaint issued against
    Gerhardt charging him with operating a motor vehicle while under
    the influence of drugs, pursuant to G. L. c. 90,
    § 24 (1) (a) (1), and traffic violations.
    2.    Discussion.   a.   Field sobriety tests.   The FSTs, which
    were designed to detect alcohol impairment, are administered and
    evaluated in a standardized manner.      The two tests primarily
    administered in the context of alcohol impairment are the WAT
    and the OLS, which are designed to assess an individual's
    balance, coordination, dexterity, ability to follow directions,
    and ability to focus attention on multiple subjects at the same
    time.5
    In performing the WAT, the subject is directed to take nine
    steps, walking heel-to-toe, along a real or imaginary straight
    line.     The subject then turns on one foot and returns in the
    same manner.    An officer administering the WAT looks for eight
    specific indicators of impairment:     losing balance while
    listening to the instructions, beginning before the instructions
    are finished, stopping to regain balance while walking, failing
    to walk heel-to-toe, stepping off the line, using arms to
    5
    There are a number of other FSTs, such as the "Romberg
    balance test," in which the subject stands with heels and toes
    together and arms at the side of the body and tips his or her
    head back slightly and estimates the passage of thirty seconds,
    and the "finger to nose test," which are less frequently used in
    the context of alcohol impairment.
    9
    balance, making an improper turn, or taking an incorrect number
    of steps.   Where the consumption of alcohol is at issue, there
    is an established correlation between performance on the test
    and blood alcohol content (BAC), with some research indicating
    that as many as seventy-nine per cent of individuals who exhibit
    two or more of these indicators have a BAC of 0.08 per cent or
    higher.
    In performing the OLS, the subject stands with one foot
    raised approximately six inches off the ground while counting
    aloud for thirty seconds.   An officer conducting the test looks
    for four indicators of impairment:   swaying while balancing,
    using arms to balance, hopping to maintain balance, and putting
    the foot down.   Research has indicated that as many as eighty-
    three per cent of individuals who exhibit two or more of these
    indicators have a BAC of 0.08 per cent or higher.
    b.   Admissibility of the FSTs in the context of marijuana.
    While using marijuana is no longer a crime in Massachusetts for
    adults who are at least twenty-one years old,6 operating a motor
    vehicle while under the influence of marijuana remains a
    criminal offense.   See G. L. c. 90, § 24.   In a prosecution for
    operating while under the influence of marijuana, it is the
    Commonwealth's burden to prove beyond a reasonable doubt, in
    6
    See St 2016, c. 334, "The Regulation and Taxation of
    Marijuana Act."
    10
    addition to the other elements of the offense, that a
    defendant's consumption of marijuana impaired his or her ability
    to drive a motor vehicle safely.   See Commonwealth v. Daniel,
    
    464 Mass. 746
    , 756 (2013), quoting Commonwealth v. Connolly, 
    394 Mass. 169
    , 173 (1985) (in prosecution for operating under
    influence of alcohol or marijuana, the Commonwealth "need not
    prove that the defendant actually drove in an unsafe or erratic
    manner, . . . [but] it must prove a diminished capacity to
    operate safely").
    Unlike alcohol, marijuana does not act as a general central
    nervous system depressant, impairing functions throughout the
    body.   Nonetheless, the primary psychoactive substance in
    marijuana, tetrahydrocannibol (THC), is known to have an impact
    on several functions of the brain that are relevant to driving
    ability, including the capacity to divide one's attention and
    focus on several things at the same time, balance, and the speed
    of processing information.   While not all researchers agree, a
    significant amount of research has shown that consumption of
    marijuana can impair the ability to drive.    There is ongoing
    disagreement among scientists, however, as to whether the FSTs
    are indicative of marijuana impairment.   In recent years,
    numerous studies have been conducted in an effort to determine
    whether a person's performance on the FSTs is a reliable
    11
    indicator of impairment by marijuana.7     These studies have
    produced mixed results.8     For example, researchers found that the
    FSTs were mildly sensitive to the effects of marijuana, with the
    OLS being the most sensitive.     That study, however, also
    indicated that the OLS produced numerous false positives.9       Other
    researchers found that the OLS was a somewhat more reliable
    indicator of marijuana impairment than the WAT.10    In a more
    recent study, by contrast, a different group of researchers
    found that the WAT was a better indicator of marijuana
    impairment than the OLS.11    Researchers conducting another study
    found that marijuana significantly impaired performance on the
    7
    The judge noted several of these studies in his findings
    on remand from this court. In addition, both parties provided
    numerous such studies in the record, and one of the amici did as
    well.
    8
    The number of studies in this field is vast; we cite only
    a few representative examples.
    9
    Bosker, Theunissen, Conen, Kuypers, Jeffery, Walls,
    Kauert, Toennes, Moeller, & Ramaekers, A Placebo-Controlled
    Study to Assess Standardized Field Sobriety Tests Performance
    During Alcohol and Cannabis Intoxication in Heavy Cannabis Users
    and Accuracy of Point of Collection Devices for Detecting THC in
    Oral Fluid, 223 Psychopharmacology 439, 443-444 (2012) (Bosker).
    10
    Papafotiou, Carter, & Stough, An Evaluation of the
    Sensitivity of the Standardized Field Sobriety Tests (SFSTs) to
    Detect Impairment Due to Marijuana Intoxication, 180
    Psychopharmacology 107, 113 (2005) (Papafotiou).
    11
    Declues, Perez, & Figueroa, A 2-Year Study of Delta-9-
    tetrahydrocannabinol Concentrations in Drivers: Examining
    Driving and Field Sobriety Test Performance, 61 J. Forensic
    Sciences 1664, 1669 (2016).
    12
    HGN, the WAT, and the OLS.12    Other studies have shown no
    correlation between performance on the HGN and consumption of
    marijuana, even where the OLS or WAT showed some sensitivity to
    marijuana consumption,13 while others have found no correlation
    between the consumption of marijuana and any of these FSTs.14
    As a result of these varied results, some researchers have
    suggested development of another group of FSTs, combining the
    currently less-frequently used Romberg stand test and the nose-
    touch test, see note 5, supra, with a to-be-developed test on
    pupil constriction,15 or adding a scoring factor of head
    movements or jerks to the standard FSTs.16    Other researchers are
    working on a tongue or cheek swab test that directly measures
    levels of THC shortly after consumption.17    It is clear from the
    above, as the judge stated in his findings on remand, that the
    scientific community has yet to reach a consensus on the
    12
    Papafotiou, supra at 111-113.
    13
    Hartman, Richman, Hayes, & Heustis, Drug Recognition
    Expert (DRE) Examination Characteristics of Cannabis Impairment,
    92 Accident Analysis and Prevention 219, 226 (2016) (Hartman).
    14
    See generally Neavyn, Blohm, Babu, & Bird, Medical
    Marijuana and Driving: a Review, 10 J. Med. Toxicol. 269
    (2014); Jones, Donnelly, Swift, & Weatherburn, Driving Under the
    Influence of Cannabis: The Problem and Potential
    Countermeasures, 87 Crime & Justice Bulletin 1 (2005).
    15
    See Hartman, supra at 226.
    16
    See Papafotiou, supra at 108.
    17
    See Bosker, supra at 442, 445.
    13
    reliability of FSTs to assess whether a driver is under the
    influence of marijuana.
    The lack of scientific agreement, however, does not, by
    itself, resolve the question whether a driver's performance on
    an FST is relevant evidence in a trial on a charge of operating
    under the influence of marijuana.   " The relevance threshold for
    the admission of evidence is low.   'Evidence is relevant if it
    has a "rational tendency to prove an issue in the case,"'"
    Commonwealth v. Arroyo, 
    442 Mass. 135
    , 144 (2004), quoting
    Commonwealth v. LaCorte, 
    373 Mass. 700
    , 702 (1977), or to
    "render a 'desired inference more probable than it would be
    [otherwise],'"   Arroyo, supra, quoting Commonwealth v.
    Fayerweather, 
    406 Mass. 78
    , 83 (1989).   To be relevant, evidence
    "need not establish directly the proposition sought; it must
    only provide a link in the chain of proof."    Commonwealth v.
    Sicari, 
    434 Mass. 732
    , 750 (2001), cert. denied, 
    534 U.S. 1142
    (2002), quoting Commonwealth v. Yesilciman, 
    406 Mass. 736
    , 744
    (1990).
    The absence of scientific consensus regarding the use of
    standard FSTs in attempting to evaluate marijuana intoxication
    does not mean that they have no probative value.    A police
    officer makes numerous relevant observations in the course of an
    encounter with a possibly impaired driver.    There is no doubt
    that an officer may testify to his or her observations of, for
    14
    example, any erratic driving or moving violations that led to
    the initial stop; the driver's appearance and demeanor; the odor
    of fresh or burnt marijuana; and the driver's behavior on
    exiting the vehicle.
    In our view, certain of the FSTs also may provide
    information that is relevant to the question of a defendant's
    impairment, and a police officer may testify, as a lay witness,
    to his or her observations of the defendant's performance.    In
    particular, observations of the performance of the OLS and the
    WAT may be admissible as evidence of a defendant's balance,
    coordination, ability to retain and follow directions, and
    ability to perform tasks requiring divided attention, and the
    presence or absence of other skills necessary for the safe
    operation of a motor vehicle.18   We see no reason why an
    officer's observations of a defendant's behavior on being asked
    to walk a straight line or to stand on one foot should be
    18
    The HGN stands on a different footing from the FSTs that
    are directed to balance and coordination. We previously have
    held that, in a prosecution for operating under the influence of
    alcohol, "the HGN test relies on an underlying scientific
    proposition and therefore expert testimony is required." See
    Sands, 424 Mass. at 188. In addition, "there must be a
    determination as to the qualification of the individual
    administering the HGN test and the appropriate procedure to be
    followed if the HGN test results are to be admitted at trial."
    Id. We reached this result because the correlation between
    alcohol intoxication and nystagmus is not within the common
    experience of jurors. Id. In the context of marijuana, any
    correlation between nystagmus and intoxication is even further
    beyond jurors' common knowledge and experience.
    15
    excluded because the scientific community's understanding of
    precisely how this correlates with marijuana use is still
    evolving.   We are not persuaded, however, that the FSTs can be
    treated as scientific tests establishing impairment as a result
    of marijuana consumption.     The scientific community has not
    reached a consensus as to whether a defendant's performance on
    any combination of FSTs, or on any individual FST, is correlated
    with marijuana use or impairment.
    The unsettled state of the scientific research suggests
    that FST evidence neither should be treated as a definitive test
    of impairment nor excluded entirely from consideration by the
    finder of fact.   Cf. Commonwealth v. Thomas, 
    476 Mass. 451
    , 464
    (2017) (where there is no consensus that simultaneous display of
    photographs is inferior to sequential display, "the
    decision . . . is best left to law enforcement, and the choice
    will continue to bear on the weight of the identification, but
    not on its admissibility").     Moreover, that marijuana can cause
    impairment of skills necessary to driving, such as coordination,
    concentration, and the ability to divide one's attention among
    multiple tasks is within the common experience and knowledge of
    jurors.   A police officer testifying to a defendant's
    performance on these FSTs therefore need not be qualified as an
    expert, and such evidence may be admitted without satisfying the
    Daubert-Lanigan requirements.     A police officer may not suggest,
    16
    however, on direct examination that an individual's performance
    on an FST established that the individual was under the
    influence of marijuana.19   Likewise, an officer may not testify
    that a defendant "passed" or "failed" any FST, as this language
    improperly implies that the FST is a definitive test of
    marijuana use or impairment.20
    Indeed, the word "test" itself inadvertently may lend "an
    aura of scientific validity."    See United States v. Horn, 
    185 F. Supp. 2d 530
    , 559 (D. Md. 2002).    We recognize, nonetheless,
    that it is not practicable to eliminate the concept of testing
    entirely from trial testimony.     The FSTs are used as means to
    evaluate a defendant's ability to perform discrete tasks which
    are correlated to skills required to safely drive a vehicle.
    See Webster's New Universal Unabridged Dictionary 1951 (2003)
    (defining "test" as, inter alia, "a set of questions, problems,
    or the like, used as a means of evaluating the abilities,
    19
    Here, for example, a trooper testified at the motion
    hearing that "the results of the [WAT and OLS] indicated that
    Gerhardt was impaired." This testimony would not be admissible
    at trial.
    20
    On cross-examination, defense counsel may challenge a
    police officer's testimony concerning a defendant's performance
    of an FST or any portion of an FST. See S.L. Jones, Drunk
    Driving Defense, §§ 3.33-3.48 (2016-2017 ed.). See also id. at
    §§ 3.49-3.54. We do not bar defense counsel from eliciting from
    the officer his or her subjective evaluation of the defendant's
    performance, but we stress that defense counsel makes this
    strategic decision at his or her own peril, and opens the door
    to redirect examination by the Commonwealth on the same topic.
    17
    aptitudes, skills, or performance of an individual or group;
    examination," and "a set of standardized questions, problems, or
    tasks designed to elicit responses for use in measuring the
    traits, capacities, or achievements of an individual").     An
    officer administering the WAT, for example, assesses a
    defendant's ability to take nine steps, walk heel-to-toe on a
    straight line, turn around, and return in the same manner.       In
    some sense, the officer thereby "tests" (measures, examines,
    evaluates, assesses, or, at a minimum, observes) the driver's
    physical balance and coordination, as well as his or her mental
    ability to understand and follow directions and to perform
    divided-attention tasks, albeit not in the same way that a
    chemist in a laboratory tests a sample for the presence of a
    particular substance.   In all circumstances, however, it must be
    made clear to the fact finder that the WAT, the OLS, and the
    other FSTs do not directly test marijuana impairment.     The FSTs
    are a means of evaluating a defendant's balance, coordination,
    and other skills specific to that test.   In addition, a witness
    testifying to the performance of FSTs in the context of
    marijuana intoxication should refer to a driver's performance on
    "roadside assessments," so as not to suggest that they function
    as scientific validation of a defendant's sobriety or
    intoxication.
    18
    We emphasize as well another consequence of the lack of
    consensus regarding the FSTs:   the fact that the FSTs cannot be
    treated as scientific "tests" of impairment means that evidence
    of performance on FSTs, alone, is not sufficient to support a
    finding that a defendant's ability to drive safely was impaired
    due to the consumption of marijuana, and the jury must be so
    instructed.21
    c.   Lay testimony on the effects of marijuana.   We also are
    asked whether a police officer may testify, without being
    qualified as an expert, to the effects of marijuana consumption
    and may offer an opinion that a defendant was intoxicated by
    marijuana.   We conclude that an officer may not do so.
    "A lay opinion . . . is admissible only where it is
    '(a) rationally based on the perception of the witness;
    (b) helpful to a clear understanding of the witness's testimony
    or the determination of a fact in issue; and (c) not based on
    scientific, technical, or other specialized knowledge.'"
    Commonwealth v. Canty, 
    466 Mass. 535
    , 541 (2013), quoting Mass.
    G. Evid. § 701 (2013).   In the alcohol context, "a lay [officer]
    . . . may offer his opinion regarding a defendant's level of
    sobriety or intoxication but may not opine whether a defendant
    operated a motor vehicle while under the influence of alcohol or
    21
    A model jury instruction regarding FSTs, to be used in
    prosecutions for operating under the influence of marijuana, is
    set forth in the Appendix.
    19
    whether the defendant's consumption of alcohol diminished his
    ability to operate a motor vehicle safely."   Canty, supra at
    544, citing Commonwealth v. Jones, 
    464 Mass. 16
    , 17 n.1 (2012).
    Such lay opinion testimony is proper because it is not based on
    scientific, technical, or other specialized knowledge that would
    require expert testimony, but, rather, lies within the realm of
    common experience.   We long have observed that "[t]he 'effects
    of liquor upon the minds and actions of men are well known to
    everybody.'"   Commonwealth v. Wall, 
    469 Mass. 652
    , 671 (2014),
    quoting Commonwealth v. Taylor, 
    263 Mass. 356
    , 362 (1928).      See
    Canty, supra at 542, quoting Holton v. Boston Elevated Ry. Co.,
    
    303 Mass. 242
    , 246 (1939) ("'the principal objective symptoms
    [of alcohol intoxication] are so well known' that we consider
    the lay opinion to have probative value").
    No such general knowledge exists, however, as to the
    physical or mental effects of marijuana consumption, which vary
    greatly amongst individuals.   On remand, the District Court
    judge reported in his findings of fact, based on expert
    testimony presented by both sides and numerous scientific
    studies, as well as existing case law in Massachusetts, that
    "[n]o studies have concluded that any specific characteristics
    are routinely found in people who have used marijuana and were
    impaired.   Manifestations of impairment may differ between
    subjects who are under the influence of liquor and those who are
    20
    under the influence of marijuana, depressants, or stimulant
    substances.    The judge found further that some scientific
    studies had identified "four prevalent physical characteristics
    common among those who were determined to be cannabis-positive
    drivers . . . These physical characteristics are red and/or
    bloodshot eyes, a lack of convergence, eyelid tremors, and
    drowsiness."    He determined, however, that no testimony admitted
    at the Daubert-Lanigan hearing related these physical
    characteristics "to an inference of impaired driving by reason
    of marijuana use.    Further, no scientific studies validating
    these specific physical characteristics as symptomatic of
    impaired driving by reason of marijuana use were entered into
    evidence."    Our review of the record confirms that the judge’s
    findings regarding lay opinion evidence are supported by the
    documentary evidence and in the studies submitted to us.
    Where there is no scientific consensus on what, if any,
    physical characteristics indicate marijuana intoxication, no lay
    opinion can be admissible as common knowledge or understanding
    on that subject.    A lay witness may testify concerning a
    defendant's observable appearance, behavior, and demeanor, but
    may not offer an opinion as to the defendant's sobriety or
    intoxication.22    See State v. Schories, 
    827 N.W.2d 659
    , 666 (Iowa
    22
    We caution the Commonwealth that "a prosecutor who
    elicits from a police officer his or her special training or
    21
    2013) (expert testimony preferred on cause of intoxication for
    substances other than alcohol); State v. Noback, 
    309 Mont. 342
    ,
    346 (2002) ("we are not persuaded that lay people are
    sufficiently knowledgeable about common symptoms of drug
    consumption . . . to offer lay opinion testimony"); State v.
    Bealor, 
    187 N.J. 574
    , 587 (2006) (court declined "to place lay
    opinion testimony regarding marijuana intoxication on the same
    footing as lay opinion testimony as to alcohol intoxication").
    See also Commonwealth v. Sliech-Brodeur, 
    457 Mass. 300
    ,
    330 & n.43 (2010) (lay witness may not testify that individual
    suffers from mental illness, but may testify to observed
    behavior).
    With respect to the question of jurors' use of their own
    common sense, we recognize that jurors are the ultimate arbiters
    of the facts.   See Commonwealth v. Lykus, 
    367 Mass. 191
    , 197
    (1975).   As a general rule, trial judges routinely instruct
    jurors, and jurors are urged by counsel, "not [to] leave their
    common sense outside the jury room."     See Commonwealth v.
    Mutina, 
    366 Mass. 810
    , 820 (1975).     Jurors may use their common
    sense in evaluating whether the Commonwealth introduced
    expertise in ascertaining whether a person is intoxicated risks
    transforming the police officer from a lay witness to an expert
    witness on this issue, and the admissibility of any opinion
    proffered on this issue may then be subject to the different
    standard applied to expert witnesses." See Commonwealth v.
    Canty, 
    466 Mass. 535
    , 541 n.5 (2013).
    22
    sufficient evidence to satisfy its burden of proof.    See
    Commonwealth v. Cole, 
    380 Mass. 30
    , 35-36 (1980) (in context of
    criminal responsibility, jurors may rely on facts and
    circumstances surrounding crime to determine whether
    Commonwealth established defendant's sanity).    We rely on the
    judge's limiting instructions to inform jurors about the proper
    use of FST evidence.   See Commonwealth v. Jackson, 
    384 Mass. 572
    , 579 (1981).
    Conclusion.    We answer the reported questions as follows:
    1. "No." Police officers may not testify to the
    administration and results of FSTs as they do in operating
    under the influence of alcohol prosecutions. Police
    officers may testify to the administration of "roadside
    assessments" in the manner set forth in this opinion.
    2. "No." A lay witness may not offer an opinion that
    another person is "high" on marijuana.
    3. "Yes." A police officer may testify to observed
    physical characteristics of the driver such as blood shot
    eyes, drowsiness, and lack of coordination. The officer is
    not permitted to offer an opinion that these
    characteristics mean that the driver is under the influence
    of marijuana.
    4. "Yes." Jurors are permitted to utilize their
    common sense in assessing trial evidence.
    The case is remanded to the District Court for further
    proceedings consistent with this opinion.
    So ordered.
    Appendix.
    Model Jury Instruction Regarding Roadside Assessments for Use in
    Prosecutions for Operating Under the Influence of Marijuana
    You heard testimony in this case that the defendant, at the
    request of a police officer, performed or attempted to perform
    various roadside assessments, such as [Here outline the nature
    of the evidence, e.g., walking a straight line, balancing on one
    foot]. These roadside assessments are not scientific tests of
    impairment by marijuana use. A person may have difficulty
    performing these tasks for many reasons unrelated to the
    consumption of marijuana.
    It is for you to decide if the defendant's performance on
    these roadside assessments indicate that his [her] ability to
    operate a motor vehicle safely was impaired. You may consider
    this evidence solely as it relates to the defendant's balance,
    coordination, mental clarity, ability to retain and follow
    directions, ability to perform tasks requiring divided
    attention, and other skills you may find are relevant to the
    safe operation of a motor vehicle.
    It is for you to determine how much, if any, weight to give
    the roadside assessments. In making your determination, you may
    consider what the officer asked the defendant to do, the
    circumstances under which they were given and performed, and all
    of the other evidence in this case.
    Finally, evidence of how a defendant performed in roadside
    assessments, standing alone, is never enough to convict a
    defendant of operating under the influence of marijuana.