When a Bright-Line Rule Crosses a Gray Area: The Problem with IQ in Louisiana’s First-Degree Rape Statute

By Jo Neuman, Issue Editor 


Louisiana defines “rape” as an act of sexual intercourse without the lawful consent of the other person.[1] Penalties increase based on specific criteria,[2] and a conviction for first-degree rape carries a life sentence without benefit of parole.[3] The statute also deems certain persons incapable of consenting, such as children under the age of 13.[4]


In 1997, the legislature added mentally infirm victims to those deemed unable to consent[5] and defined “mental infirmity” as “a person with an intelligence quotient of seventy or lower.”[6] Mentally disabled individuals are estimated to be four to ten times more likely to be victimized sexually than members of the general population.[7] Legislators likely considered this fact when they added protection for such victims to the first-degree rape statute.


The constitutionality of this definition was recently challenged, and the Louisiana Supreme Court remanded the case to the district court for consideration of the defendant’s claim that the statute is unconstitutional because it establishes a threshold intelligence quotient (“IQ”) score as the sole determinant of mental infirmity.[8] The problem is not trying to protect this class of particularly vulnerable individuals, but rather the specific definition of mental infirmity that appears to criminalize all sexual activity with a person whose IQ is 70 or lower.[9] In light of medical science and recent jurisprudence, the provision is probably unconstitutional. Regardless of the result in the pending case, the Louisiana legislature should revise the definition to align with medical science and recent jurisprudence.[10]


Medical Science and IQ Uncertainty

Medical science recognizes that intellectual disability involves more than an IQ score. To be intellectually disabled, the American Psychiatric Association says a person must have deficits in both general intellectual ability and adaptive functioning in one or more areas of daily life with onset occurring during the developmental period.[11] Two people with the same IQ may differ significantly in their abilities to function in society.[12]


Medical science also acknowledges that IQ scores are not exact and represent a range with a margin of error of five points.[13] Thus, the range for an IQ score of 70 would be between 65 and 75.[14] Medical experts also note an IQ score should not be considered in isolation and that “clinical judgment is needed” to interpret the results of an IQ test.[15] Further, IQ scores “are approximations of conceptual functioning but may be insufficient to assess reasoning in real-life situations . . . a person with an IQ score above 70 may have such severe adaptive behavior problems . . . that the person’s actual functioning is comparable to that of individuals with a lower IQ score.”[16] As a result, individuals with IQs above 70 could be less capable of consenting to sexual activity than persons with a lower IQ score,[17] yet the statute as written offers these individuals no protection.


Conversely, persons with IQs lower than 70 might be capable of consenting to sexual activity because of the level of their adaptive functioning, yet the plain language of the statute criminalizes such conduct. Advocates opine that intellectually disabled adults are “sexual beings”[18] and should not be categorically precluded from consenting to sexual activity.[19] They contend everyone “has the right to exercise choices regarding sexual expression and social relationships” and having an intellectual disability “regardless of severity, does not, in itself, justify loss of rights related to sexuality.”[20] In light of the inherent medical uncertainty in a given IQ score, evaluation of a person’s ability to consent should be individualized and not tied to a bright-line cutoff score.


Jurisprudential Findings on IQ

The United States Supreme Court has taken note of medical science in holding that IQ alone is insufficient to determine whether a defendant in a capital case is intellectually disabled.[21] The Florida Supreme Court had held defendants with IQs over 70 were categorically not intellectually disabled and therefore eligible for the death penalty.[22] The Court found it impermissible to rely on “an IQ score as final and conclusive evidence of a defendant’s intellectual capacity, when experts in the field would consider other evidence.”[23] The Court specifically referenced the definition from the DSM-5, which requires consideration of deficits in adaptive functioning in addition to sub-average intelligence.[24]


Even before the United States Supreme Court rendered its decision in Hall, the Louisiana Supreme Court declined to set a bright-line IQ cutoff score for evaluating whether a defendant was intellectually disabled for purposes of capital punishment.[25] The court considered medical science noting that a defendant must show “subaverage intellectual functioning existing concurrently with deficits in adaptive behavior.”[26] Further, the court acknowledged IQ scores are not exact and represent a range in which a person’s actual score falls.[27] In her concurrence, Justice Knoll stated that Louisiana does not apply a strict numerical cutoff to IQ scores when evaluating intellectual disability.[28] Despite this judicial recognition, the first-degree rape statute still employs a bright-line IQ cutoff score.[29]


Prior Legislative Recognition

The Louisiana legislature has not been silent on this issue. In 2003, it enacted a rule for determining when defendants in capital cases are intellectually disabled wherein it used a definition of  intellectual disability substantially similar to what is contained in the DSM-5 with no reference to an IQ cutoff score.[30] Additionally in 2011, the legislature explicitly declined to add an IQ cutoff score to proposed revisions to the sexual battery statutes.[31] Despite revising the first-degree rape statute several times, the legislature has not revised the definition of mental infirmity contained therein.



Determining intellectual disability is a gray area that does not lend itself to relying solely on a bright-line IQ cutoff score. Both the United States Supreme Court and the Louisiana Supreme Court have recognized IQ scores are imprecise, and relying on an IQ score without taking into account other factors considered by medical experts is improper.[32] Removing this bright line and allowing for the possibility that an intellectually disabled individual can consent will help ensure a defendant is not automatically facing a potential life sentence based solely on the other person’s IQ. This change would likewise afford greater protection to a victim with an IQ over 70 who is found unable to consent because of deficits in adaptive functioning. Furthermore, by eliminating IQ from the definition of mental infirmity, the legislature will align the first-degree rape statute with medical science and jurisprudential findings and ensure consistency in Louisiana’s criminal statutes.

[1] La. Rev. Stat. § 14:41 (2016).

[2] Compare Id. § 14:42, and § 14:42.1, with § 14:43 (sentences range from “not more than twenty-five years” to mandatory life imprisonment).

[3] Id. § 14:42(D).

[4] Id. § 14:42(A)(4).

[5] 1997 La. Acts 757.

[6] La. Rev. Stat. § 14:42(C)(2).

[7] Deborah W. Denno, Sexuality, Rape, and Mental Retardation, 1997 U. Ill. L. Rev. 315, 320; Joan Petersilia, Invisible Victims: Violence Against Persons with Developmental Disabilities, 27 Hum. Rts. 9, 9 (2000).

[8] State v. Mosley, No. 2016-1350, 2016 WL 7448268, at *1 (La. Nov. 29, 2016).

[9] La. Rev. Stat. § 14:42(C)(2).

[10] The legislature should also revise other provisions in this statute, including updating the definition of physical infirmity and removing the capital punishment provisions in light of the holding in Kennedy v. Louisiana, 554 U.S. 407 (2008), but discussion of those provisions is beyond the scope of this comment.

[11] Am. Psychiatric Ass’n, Diagnostic and Stat. Manual of Mental Disorders: DSM-5, 33 (5th ed. 2013). General intellectual ability is assessed based on IQ testing. Individuals are considered intellectually disabled if their IQ scores are approximately two standard deviations below the mean. On a typical IQ test, the mean is 100, and the standard of deviation is 15, resulting in a score of approximately 70. Id. at 37.

[12] Id. at 37.

[13] Id.

[14] Id.

[15] Id.

[16] Id.

[17] Id.

[18] Claire Azzopardi-Lane & Anne-Marie Callus, Constructing Sexual Identities: People with Intellectual Disability Talking About Sexuality, 43 Brit. J. Learning Disabilities 32, 35 (2014).

[19] Sexuality: Joint Position Statement of AAIDD and The Arc, Am. Ass’n of Intell. & Dev. Disabilities, http://aaidd.org/news-policy/policy/position-statements/sexuality [https://perma.cc/SGL3-TL38] (last visited Feb. 8, 2017). See also Alexander A. Boni-Saenz, Sexuality and Incapacity, 76 Ohio St. L.J. 1201, 1205 (2015) (“[T]he right to sexual expression should not be withheld due to cognitive impairment alone.”).

[20] Sexuality: Joint Position Statement of AAIDD and The Arc, supra note 19.

[21] Hall v. Florida, 134 S. Ct. 1986, 2001 (2014).

[22] Id. at 1994.

[23] Id. at 1995.

[24] Id. at 1994.

[25] State v. Dunn, 41 So. 3d. 454 (La. 2010).

[26] Id. at 461.

[27] Id. at 470.

[28] Id. at 475 n.1.

[29] La. Rev. Stat. § 14:42 (2016).

[30] La. Code. Crim. Proc. art. 905.5.1 (2016) (characterizing intellectual disability as “[d]eficits in intellectual functions . . . confirmed by both clinical assessment and individualized, standardized intelligence testing . . . [and d]eficits in adaptive functioning”).

[31] H.B. 86, 2011 Leg., Reg. Sess. (La. 2011) (as originally introduced, this bill defined “mental infirmity” as “a person who has an intelligence quotient of seventy or lower,” but amendments adopted before its enactment removed all references to IQ).

[32] Hall v. Florida, 134 S. Ct. 1986, 2001 (2014); Dunn, 41 So. 3d at 470.