Professor David S. Cohen’s analysis of several abortion cases explores a legacy of the Planned Parenthood of Southeastern Pennsylvania v. Casey ruling, namely ambiguity over the definition of “a large fraction.”

In Casey, the U.S. Supreme Court found that an abortion statute is unconstitutional on its face, if “in a large fraction of the cases” where the law applies, women face a substantial obstacle to undergoing the procedure.

Cohen and co-author Jeffrey B. Bingenheimer of George Washington University’s Milken Institute School of Public Health examine the equivocal nature of that test in “Abortion Rights and the Largeness of the Fraction 1/6,” which appeared in the University of Pennsylvania Law Review Online.

In 2015, the article notes, the Fifth Circuit upheld restrictions that slashed the number of licensed abortion clinics in Texas from more than 40 to eight or nine. The Fifth Circuit concluded that restrictions requiring one in six women to travel 150 miles or more to reach a licensed abortion clinic do not affect “a large fraction” of prospective patients and are therefore constitutional.

The Supreme Court’s 2016 opinion in Whole Woman’s Health v. Hellerstedt reversed the Fifth Circuit ruling without specifically answering the question: what constitutes a “large fraction?”

Amid a wave of abortion restrictions enacted in many states, Cohen and Bingenheimer’s article cites numerous rulings in which courts have grappled with the question, arriving at diverse conclusions: in 2006, the Sixth Circuit ruled that restrictions creating barriers for 12 percent of Ohio women were permissible, the Eighth Circuit decided that a parental notification requirement affecting 18 percent of minors was unconstitutional and a district court in Indiana ruled that a counseling requirement that would reduce those obtaining abortions by 11 to 14 percent was also impermissible.

Cohen and his co-author conducted empirical research that examined whether and when individuals view fractions as large. They created a survey that asked more than 500 demographically diverse participants a variety of hypothetical questions requiring them to characterize the size of fractions: if an employer asks workers to donate 1/6 of their pay toward a pet cause, if 1/6 of pills in a Tylenol bottle contain cyanide, if 1/6 of gun stores in a community are closed or if one in 20 neighbors living within 10 miles are registered sex offenders. 

The authors found that “the extent to which people regard 1/6 as a large fraction depends strongly on the context in which that fraction is presented” as well as the degree to which the number meets or exceeds their expectations in that context.

Because “large” is a relative adjective, subject to numerous contextual interpretations, Cohen and his co-author argue that judges who evaluate anti-abortion restrictions in the future must avoid allowing their views on the matter to cloud their analysis of the proportion of women affected by restrictive laws.