mr chief justice in may please the court in actions first is for ginia this court held that the constitution bars executing persons with mental retardation that is persons would significantly average intellectual function concurrent with deficits in adaptive behavior with an onset before the age of eighteen because of the standard error of measurement that's inherent in i q tests it is universally accepted that persons with obtained scores of seventy one to seventy five can and often do have mental retardation when those three prongs are met the statistical error of measurement or s a line has to be drawn somewhere and we did say that we would leave it up to the states to determine the standards for this issue so what's the rule we announced today we'd sell them seven not ok but seventy five would i'm well quite sure how would you announce them let me first take seek some issue with all due respect with your characterization of at what this court said in adkins is not that we leave it to the states to establish the standards for the clinical condition of mental retardation you what you said quoting ford is we leave it to the states to we leave to the states the task of developing appropriate ways to enforce the constitutional restriction that we announce the rule that we advocate is and the only real question presented in this case is just this if a state conditions the opportunity to demonstrate mental retardation on obtained i q test scores it cannot ignore the measurement error that is inherent in those scores that is a feature statistical feature of the test instrument and what we didn't we didn't base our decision hakon's upon a study of what the american  psychiatric association and other medical associations considered to be mental retardation we based it on what what was the general rule that states had adopted and a large number of states had adopted seventy as the criteria i mean the criterion is what do the american people think is the level of mental retardation that should make it impossible to impose the death penalty we didn't look for the answer to that question to the a p a or any of the other medical associations we looked to what the states did now what has changed in what the states do anything  have i would like to respond with four points and i hope desperately i'll remember them first of all what this court said was this court number one it made clear as it is reiterated in miller versus alabama and graham versus florida that while a consensus or a perceived consensus among the states is important the ultimate test is this court's conclusion about what the eighth amendment does or doesn't allow in making that determination at page three eighteen of this court's opinion in atkins this court after reciting in footnote three the virtually identical clinical definitions of mental retardation and footnote five pointing out that seventy to seventy five is the established cutoff for mental retardation this court said the following quote clinical definitions of mental retardation require and the recited the three tests because of their impairments mentally retarded persons by definition that is by the clinical definition have diminished capacity to understand and it recited all the other disabilities that made the imposition of the death penalty for persons with that excuse me with that clinical condition unconstitutional now as to what the states did the court did refer to i believe eighteen state statutes not a single one of those state statutes and not a single decision of the highest court of any state or any any state applied seventy or two standard deviations from the mean without reference to the only statute that addressed it in two thousand and two when this court decided at of measurement which is a stablished by the creators of the test it is not something that clinicians dream up it's not something that is decided by the a i d d or the american psychiatric association it inherent in the test and all clinicians are told both professional associations make clear because it is simply a statistical fact it must be taken into account such is so incapable of controlling his actions that he shouldn't be subject to the death penalty is that is that what they're looking for when they establish seventy to seventy five what are they looking for well what their they are looking for i mean intelligence tests supply a i mean they were created for the definition of clinical definition of mental retardation they were created as an order to determine a proxy for true intellectual function and therefore are a true i q test score i mean the general quote i'm not talking about i q tests in general i'm talking about why do they pick they used to pick seventy now they pick between seventy and seventy five is the upper limit would flop or limit for want i assume it is for people who would profit from medical treatment that isn't that there are many reasons why a person q that is a person's intelligent intellectual functioning may be important for a whole variety of reasons medical psychological developmental and as a component of the clinical condition of mental retardation the concept the statistical concept of a standard error of measurement has applies to all forms of testing and has nothing to do the death penalty and no i mean i am sure that started out with in your view does the constitution permits a state to establish any hard cut off on say seventy six can it do that i think it can because that falls peak because  state is using and obtained i q test score as a proxy for true intellectual function it has to take into account the standard error of measurement and therefore states like mississippi and oklahoma that in fact a stablish a cut off of seventy five in our view is constitutional as this court announced the class of individuals in atkins so that is  saying what i'm saying why when you say the standard of misery you're talking about a degree of confidence right and your submission is that you need to have a ninety five percent degree of confidence well  measurement it's not it's not this is not my submission this is the universe and i'm just trying to figure out what it means if that's exactly what it means is that someone for example with an eye in obtained i q of test score of seventy one as mr hall received has a ninety five percent probability that his score will be between seventy six so why is ninety five percent where does that come from that under evidence why why are you picking ninety five percent why isn't it in ninety percent i'm not doing any picking or why did the other why did the the organizations pick ninety five percent it's been ninety five it's been two standard error of two s c m which is ninety five percent for decades and decades and this  recognize that consensus that universal consensus in footnote five in its opinion which in marty has the burden of persuasion on the issue of i q and what is the standard so it varies from state to state assign that burden of persuade above seventy luck and they assign that to the defendant and if they can what is the standard of proof that the defendant has to meet so i the short answer is i believe will either come to yes so that you see were going but we believe that it is entirely constitutional for the state to assign the burden of proving mental retardation on the defendant and in so far as the clinical definition recognized by this court and act is a three part conjunctive test i think it's fair to say that a logical consequence of that is that as to every component the burden may constitutionally be placed on the defendant now the burden with respect to prong warrant is the burden of proving significantly so the average intellectual functioning of which a true i q score is a probabilistic piece of evidence but i don't think why can't the state if you told me that a state can establish a hard cut off and you told me that the state can assign the burden to the defendant now in the case of someone who scores seventy five is it not the case that there's roughly there's no more than a two point five percent chance of that person's real i q is seventy so how does that square with any burden of proof it might be and any standard of proof that might be assigned on that on that point that's what i don't understand about your argument i think here let me see if i can explain this first of all we're talking i mean this is a man who has a seventy one and i understand what i'm talking about the general issue has had a clue as to the general issue let me let me let me say it this way the whole idea behind measurement error is that you can't make a valid judgment that somebody doesn't have a true score of seventy or below if the obtains score is within the measurement error and even more fundamental than that of the your question suggests in the state suggestion suggests that diagnosing mental retardation which is the constitutional inquiry is just a probabilistic inquiry into a person's quote true i  but true i q scores themselves are a statistical concept it's the score that you would get on a hypothetical test that had no measurement error but true and this is the point true i q is not the same as intellectual function and i q tests themselves however perfect they may be don't perfectly capture a person's intellectual function just why have to stand that argument but that doesn't seem to me consistent with your point that a state can establish a hard cut off seventy six that's the end of seventy six on an i q test that's the end of the inquiry the person does not does not does not qualify under atkins so what i'm  would not be a standard i would indorse but i believe that in light of the consensus test that all professional organizations apply that was recognized in atkins a board that is a ball of the standard error of measurement of two standard deviations above the mean would be ok but the point the converse point it seems to me is not true which is we know for a fact that many many people who obtain test scores of seventy one to seventy five in fact have mental retardation and if i just may point out that in this case there were six experts who fully examined mr hall or supervised a full examination of mr hall they were cognizant of the i q test scores that he had received and each one of them o pined without hesitation that he had mental retardation functional mental retardation jessica definitively did make a finding that he did not agreement that there could be a proffer in some expeditious manner and that's a joint appendix one fifty eight we up one of the two grounds that we appealed to the florida supreme court on in addition to the hard cut off at seventy was the fact that in fact an expeditious proffer did not in fact permit us to put on all of our evidence about prongs two and three and the florida supreme court and this is page one twenty five of the joint appendix said we don't need to consider that question because we uphold the rule in cherry things you're correct part of the expeditious proffer of the expeditious proffer was limited to the testimony of two i believe actually only one of the experts who examined and did the adaptive testing function and knapp expert did say that he didn't test in prison now as but there is a again a universal professional consensus that adaptive functioning is tested by adaptive functioning in the real world not adaptive functioning that occurs on after thirty five years on death row and in fact we also know to a clinical certainty that because mental retardation is a condition that is both developmental and not transients that is there has to be an onset demonstrated onset during the developmental period but one doesn't even form the condition of mental retardation on like for example mental illness that if you talk about the condition with mental disability that the involved here want to go back to something you've said in response to just the question was along the lines of what does it mean to have a disorder under the d s m obviously one thing that means is that the scholars can talk about it that they can all focus on the same subject does it have any meaning other than that that is it is an objective index an exhibit an objective characterization that certain people have certain mental conditions is that what it means that's exactly what it means justice kennedy what it means is it is a as this court recognized it is a clinical condition on like for example insanity or confidence and there's clinical is there any is there any evidence that society has in general i would give substantial references to the psychiatric profession in this respect are there any studies on that as anyone can look to decide to see that that's true or not true i i'm actually not aware of anything that suggests that one that society doesn't look to professional evaluations to do business and in fact if one looks only at florida's system florida it uses mental retardation and as a determinant for things other than the death penalty uses that can the existence of the condition for educational remediation vocational rehabilitation and everything and in those instances as we point out in our brief step the florida vote florida does apply the standard error of measurement and we have later in the week an argument about economic a psychologist and psychiatrist any more than we are any less than we do with commas oh i think it has to be much much more because as this court has pointed out this is a clinical condition it's a condition that can only  be appropriately diagnosed by professionals who are changing and they change their mind counsel is a p a is the same organization that once said that homosexuality was a  disability and now says it's perfectly normal they change their moods just disk and they have changed their minds as to whether seventy or seventy five is the is the new test for mental retardation the latter is not true it's the standard two things that are not in dispute in this case we're only here talking about pulling one which is significantly sub average intellectual functioning and nothing else and everyone agrees all the states agree they all agreed at the time act and it was decided that there that the clinical condition is defined by three elements and that the first element significantly sub average intellectual functioning is defined as a person whose intellectual function is two or more standard deviations below the mean intellectual functioning of contemporary history was a society it can i take you back to a question that the chief justice asked because the chief justice said you know where does this c m come from and it is the test maker's determination that this is the margin of error that gives you a ninety five percent confidence i guess the question here or one question here is why do we have a ninety five percent why do we need a ninety five percent confidence level and you could say it either way you could say gosh we're putting somebody to death we should we should have one hundred percent confidence level or you could say as i take it justice alito was justice alito is point was well look the burgen of proof is on the defendant here anyway so a ninety five percent confidence level seems awfully high that we should you know ration it down to eighty percent so why for this purpose do we have to go with the test makers determination that five is what gives you a ninety five percent confidence level so the fact that two s c m's gives you would ninety five percent confidence level is just statistical fact i take your question to be well why does you know why do clinicians and professional associations use that well that's not really my them might use it for a wide variety of purposes the question is why it is their determination that it's useful for a wide variety of purposes to have a ninety five percent confidence level why is the state stuck with that for this purpose because the whole in this goes to the reason that they use it the reason that they use it is because of the inherent imprecision in testing in general but in particular testing for the presence of something like relic relative intellectual functioning there are so many people it is so common for people who for all variety of reasons obtain a seventy one or seventy two in fact to have mental retardation and because evidence of intellect and evaluation of intellectual function involves clinically much more than a test score i mean look what happened in this case all of the i tests that were administered all of the wechsler tests were accompanied because they fell within the standard error of measurement they were accompanied by the administration of further intelligence testing for confirmatory is that what you want that is good back to just the sort of meyer's question start mucking around with ninety five percent it's all over the law and ninety five percent is a classical measure by scientists when they have confidence th fact that the regression analysis seems to establish is in fact a fact yesterday that is in toward law that isn't whether jury trials are discriminating because they don't have black people on the jury it's all over the long so i we're not asking us to muck around with that number because i don't know what the consequences would be so that if they were not to use how we reduce it you give the same test six times and now we've reduced it from five percent if he's above seventy all t a feature is generally speaking a feature that is widely adopted as a confidence level and it is particularly important here because the constitutional guarantee announced in act ins is against the execution of persons with mental priors last point before your time expires because i do think this is important is there not another way of proving a liability suppose one about multiple tests suppose someone is given twenty five tests and twenty four times the person scores seventy six and one time the person scores seventy two weapon would you deal with how would you deal with that in a state that has a hard cut off so this is the last point that i wanted to get to and i think if you the best thing i can before my time runs out i just want to point you to page ten footnote three of our reply brief which cites the oxford handbook of i don't know clinical diagnosis or something and we've given you the pages and on those pages that explains why when you have a situation of somebody who takes more than one test the appropriate determinant is very much not the average it is what's called the composite score and the composite score is different and in fact for people below the mean below the average because you have to take into account the fact that we're question towards the mean and also the fact that a person who takes two three or four tests multiple tests change is the bell curve standard deviation so the example that's given in the oxford handbook it's very similar to this case there were four tests they averaged seventy two the composite score and there's there's a statistical explanation for how it's arrived at the composite score is sixty nine and the standard error of measurement is actually larger using a composite score so that's why as to justice briar's the last point simply averaging scores does not in fact give you a better handle the because there are so few people who score significantly below the mean on both the ball tests what clinicians use is a statistical analysis that that takes into account the different the different calculation of what a standard deviation below the mean that's not consistent with my understanding of a claim that i have a deep understanding of it but what what would be your answer to my hypothetical where there are multiple scores that are above the hard cut off but one that's below and i'll ask the state the opposite question what would you do there well we know what florida does require in your view well the eighth amendment requires that if a state chooses to use i q test scores as a proxy for intellectual functioning rather than a full inquiry into view is that a state consistent with active ends could say that if you have no up taint score on a valid properly administered up to date test that is seventy that is below seventy six you mate you may constitutionally be precluded i think many clinicians would go ahead and do adaptive functioning and other what you what do you do with multiple scores and in fact in this case we're not talking about someone who had one or two i q scores when you look at the wechsler test which is what the petitioner contends is the gold standard he had test scores of seventy one seventy two seventy three seventy four and eighty eight and as we understand what the petitioner would have this court do is to take some of those lower scores and simply subtract five points from them that's not consistent with  mean i'm not very happy having to go through this in all future cases where you have somebody who has sixty million seventy three seventy four seventy five and eighty one it i mean don't you have some more general principle other than the the particular scores in this case are good enough where we certainly think the particular scores in this case are good enough but we do we have a broader principle which is that when you're dealing with things like mental diagnosis or things in the medical field generally that there is good reason for this court to do as it has historically which is to to defer to reasonable legislative judgements but you will let me let me ask that ask you this suppose that the american psychiatric association and all other professional associations do not use the c m suppose that it seems to me with the state is saying here and declining to use that is that it declines to follow the standards that are set by the people the designed and administer and interpret the test well i have two responses to that one if the constitutional rule which we submit it's not but if there were constitutional rule that the eighth amendment required they're not saying you have to take that number and declare that person mentally intellectually challenge you just have to apply the other factors well it's a three protests so in any instance you would have to demonstrate there that's a three part task and the medical community doesn't dispute that the petitioner doesn't dispute that but to achieve a diagnosis of mental retardation you would have to demonstrate that you meet each of the three chrysler what is wrong this i'm there may be agreement among you this what athan says is there are three parts as you say one part is significantly sub average intellectual function it's the first part and so what you say is if it's above a seventy on an i q test or a couple of them that's the end of it we don't go further what they say is really i want to tell the jury something or the judge if the judge is deciding judge i have an expert here thank you expert i want to tell you your honor that that number seventy is subject to error it could be in indeed the state can do the same thing if it's sixty eight the number sixty eight is subject to error so if somebody measures sixty eight you could bring in the witness and he would say five percent of the time it's within five points either way i think that's all they want to do now there could be other ways of going about it  maybe you give the same test six times in with different questions and that may not eliminate that it might reduce the possibility of error or and there may be some other way to do it you call in a psychologist and he says ok or an expert seventy two but he still we have all the ways we have other ways not just test i think you would do the same thing if you wanted to on the downside i guess and that might lead people not to be to being executed you say and that's their position though i think and they get to do it on the up side all right what's wrong with that it doesn't sound so terrible and anyway the eighth amendment this is a this is a way of enforcing the eighth amendment this doesn't need to be i don't think an independent eighth amendment violation but go ahead that's the kind of question i would love to have some sure what's wrong with that is it substantially if you raise the limit to seventy five as mr waxman suggested you could double it's not raise the limit to seventy five what it does is it says just what i said and i don't want to repeat it when it's there at seventy they call their expert who informs the decision maker just what i said that would take a little time maybe fifteen minutes maybe a little longer but that's what they want to do right i think and and why not i mean what's so terrible about doing it what's so terrible about doing it is you would end up increasing the proportion of people with the number of people who would be eligible for a mental retardation diagnosis off only a guy who's who in fact are mentally retarded you know where you are because they're not mentally retarded there's no disagreement that seventy is the appropriate threshold here so this is almost an evidentiary matter it's a matter of what does it take to prove by clear and convincing evidence which is a standard of proof that they have as a matter of florida law and it's a standard of proof they do not challenge in this case and also to recognize is that the best measure determination and what you were cut off does is it essentially says the inquiry has to stop there and the question is how is that at all consistent with anything we ever say when it comes to the death penalty because when we have a school line of cases that says when it comes to meeting out the death penalty we actually do individualized consideration and we allow people to make their best case about why they're not eligible for the death penalty and essentially what you were cut off does this it stops that in its tracks as to a person who may or may not even have a true i q over seventy and let alone it's just people in their tracks as to who may not be mentally who may be mentally retarded well first with respect to mitigation this is this act is here in florida it's completely separate from the mitigation phase and so he does still have individualized decision making with respect to whether to have a death sentence and he still had an opportunity but he does all of that with respect to this critical question right we've said you cannot execute it was mentally retarded and he says now you are preventing me from showing the good mentally retarded because you have an i q test a part of one prong of a three prong test you have an i q test that says that not mentally retarded but you know that test may be wrong its not its be given that you are not using the margin of error well with respect to the i q test just being one part of the intellectual functional problem that is a very recent development and one of the one of the problems we have with the idea by pointing to the fact that he is the one who sees the young woman who pushed her into a car who drove the car with his accomplice following in another car and who killed her and killed another killed a policeman to later i stress could to state bring that in it's a somebody who is mentally retarded enough so mentally retarded as not to be responsible and not to be subject to the death penalty kagan question i think is a very important question that we've been talking about here about the inaccuracy to some extent of cues of course and your rule prevents us from getting a better understanding of whether that i q score is is actually good or not because you we cannot even reach the adept of a functioning whether adaptive functioning evidence can a fact the reading of the i q we submit that's not that's not the case that's why there discreet inquiries and so if you have multiple test scores or if you have one in has a very close cases doesn't it way the medical community looks at how to measure i q or what to do with i q and so the model at the very least you give somebody an i q test he scores a seventy one now he might actually have an i q of seventy one or we know from the way the standard margins of error work he might have an i q of sixty nine and you won't let him go to the happy adaptive behavior prong of the test and show that you know and and show that he can't function even the guidelines for d s m would agree that no matter what your deficits are and adaptive functioning you do not qualify for mental retardation diagnosis without also showing substantial deficits in intellectual function component of this for some time i can we don't dispute that we do know that the emphasis on i q is is decreasing and that their medical community is now suggesting that you should rely less and less on i q and they've changed not arguing for that they're just arguing that we should stay where it's always been which is using the c s well i think what they're what they're arguing is that you should you should do this you should apply the s c m in the same way the clinicians do because that's the way the clinicians do it and if you go down that road then it is very difficult to understand in a principled way where where that would stop is the case that those who use i q tests always require a ninety five percent confidence level and always must require a ninety five percent confidence level let's suppose a school  on the other end of the ice scale wants to identify gifted children and they say child is gifted if the child has an i q of one hundred thirty or above so they say if you have an obtained score of one thirty you're in you're in the gifted child program even though there is the same percentage that would be would be the case with respect to someone with an i q of seventy but really that person is below one hundred thirty would there be something wrong with their doing that no you know they example about someone to a school they can set that as high or low as they want to because they might want to be over inclusive they might want to be particularly restrictive and that's one of the areas where what we're dealing with here in the atkins context is fundamentally different because we have an adversarial process at least with respect to contested cases we have a burden of proof a clear and convincing evidence of proof it's not shared in the clinical setting and so there are a lot of reasons why it's very different to make a diagnosis in a clinical setting particularly now where the emphasis in the medical community is on providing services or making services available to people and where you don't have the same disincentive to be over inclusive the general could statute to say we're now using a threshold of sixty well this state certainly have substantial leeway i think the answer that is yes although it would be it would be more difficult to defend because i think what you'd want to do is go back and look at the  very long standing everybody has agreed that it's at seventy for many many decades maybe maybe forever so how could the state if the state that's why the state say no to that what would you look at well i think juncture when you have a fixed cutoff you have the ability to defeat the other two prongs but you're stopping them on a test based on a test score recognized by the designers of the test well we're not stopping them from putting on we're stopping is the consideration of the other problems when it's clear that the first pro care can be satisfied so i think there's been in the briefing this idea that it necessarily has to be sequenced a certain way and it doesn't if someone came in and it were undisputed that he could not satisfy the adaptive functioning prong for example then you wouldn't necessarily have to look at i q so the nicer i thought the florida if i know that that's that's correct and what happened in this case was there was a motion in limine a by the state recognizing that the that the i q scores that weren't issue here were all about seventy and so it was it sort of an ordinary evidentiary motion you know if you had it's the evidentiary ruling was certainly a recognition simply a recognition that you have to satisfy all three problems which again is a factor that happened right now today under the law of florida a similar case and there's an i q score seventy one and the prosecutor points out to the judge that the talking and the defense lawyer says your honor i would like to bring in my test expert here who will explain to you that even though this test did show seventy one there is some fairly small but significant probability of error and it could be in fact be as high as seventy six and he would like to explain to you that that's the situation and therefore  can i have him testify as the judge have to let him testify or not if i understand the hypothetical correctly you have one test score of seventy one and so without any taint test score of seventy or below he would  not then this is the dispute in the case they would like to present that expert you would say no that's right and i'd be easy back to my friends going to be sure yes by jet to my first question which i won't repeat and this man has been on death row for over thirty five years i florida has executed has been an average of twenty four point nine years on death row do you think that that is consistent with the purposes of the death penalty and it is  consistent with sounded ministration of the justice system why certainly think it's consistent with the constitution and i think that there are obvious that was my i'm sorry i apologize is that consistent with the with the purpose of the death penalty is designed to serve as a consistent with an orderly administration of justice it's consistent with the with the with good is consistent with the purposes of the death penalty certainly winter maybe you should ask us people who are eligible for the for the punishment for the for the exemption and that's inconsistent with for the purposes of the death penalty but that's just to say that it would and double the number of people eligible but some of them may be mentally retarded i seventy below i mean you don't believe that yourself right this is a tool to decide whether somebody is mentally retarded and it's a tool that functions and one of the three prong test it is the first part of the i q threshold is the first prong so you  no matter what your adaptive deficits are you must demonstrate and again here in this adversary setting you must demonstrate by clear and convincing evidence that you have an i q of seventy or below and what we believe is that if you say well there's a ninety five percent chance that my i q is somewhere between say sixty eight and seventy eight that you have not satisfied that first quote i'd like to talk about the ninety five percent confidence interval because it is not the case that you have to say with a seventy two or ninety five percent chance that you is seventy or below in fact it's a very small chance with what the confidence interval measures is that you have a ninety five percent chance that your true i q is within five points of the measured the measured i q but it's not that you would have an equal chance of having a sixty six very very small likelihood that you get that your true i q and and then with each additional test you take the odds that that's about seventy of the odds would go down so it's simply not the case that you can say well he has a seventy two so he is satisfied or even mi want to stick to it you'd have to look and say well what of that what are the odds that with that group of testing that his true like you is understand now is it possible certainly is possible it is over one hundred the you know you can exceed the ninety five percent confidence interval and nobody disputes that that the true i q is something that is incapable of being measured or incapable of it but the i q test is what the community has and it's the most objective of the three there are eight states that have both a hard cut off and a and a seventy or two standard deviations which approximates to the same thing that has been expressly recognized by the states there are a number of other states that have statutes similar to florida's but  your only score is seventy one you're out and that applies whether you eat take one test or multiple tests here i'm clear being from the supreme court's decision in cherry that quote it is a universally accepted given that  that the s c m is a universally accepted given and as such should watch it really be considered in determining whether a defendant has mental retardation what the court said was we have to read the plain meaning of the florida statute in the florida statute says two standard deviations the notion that the florida legislature or the p p may i finish my sentence the florida legislature the people of florida have made a considered decision not to account for the s c m is baseless and his bill wide by the legislative report that a company's the statute which said seventy to seventy five thank you