Total law school enrollment in 1971-72 (JD students): 91,225
Total law school enrollment in 2011-12 (JD): 146,288
Increase in law school enrollment between 1971 and 2011: 60.4%
The U.S. population increased by 51.2% between 1971 and 2011. This means that over the past 40 years law school enrollment has grown 18% faster than the US population as a whole.
However the real rate of increase in law school enrollment, relative to the size of the population cohort from which almost all law students are drawn, has been much faster:
Approximate number of people ages 22-33 in 1971: 32 million.
Approximate number of people ages 22-33 in 2011: 44.4 million. The population of people ages 22-33 was only 30.6% higher in 2011 than in 1971 – not 51.2%. (This is because by 1971 the front end of the baby boom had reached law school-attending age). So enrollment in law school has increased twice as fast over the past four decades as has the population cohort from which the vast majority of law students are drawn.
If we assume 90% of J.D. students are between the ages of 22-33, there were 82,103 such students in 1971 and 131,659 such students in 2011. This would mean .24% of people between the ages of 22-33 were JD students in 1971, and .30% of people between the ages of 22-33 were JD students in 2011. This means the odds that today somebody in the core population cohort from which law students are drawn is going to law school are about 25% higher than they were in 1971.
But phrasing the matter in this way obscures a key demographic development: Men are significantly less likely to go to law school today than they were 40 years ago, while women are vastly more likely to do so (The latter point is well understood. The former would, I think, come as a surprise to most people).
There were about 17 million men in the core age cohort for law school attendance in 1971. Assuming 90% of the men attending law school in 1971 were in this age group, this means 74,392 men ages 22-33 were attending law school in 1971. Thus approximately .44% of men in the core age cohort in the US were attending law school in 1971. There were approximately 22.2 million men in the core age cohort for attending law school in 2011. Assuming 90% of the men attending law school were in this age group, 70,223 such men were attending law school in 2011. Approximately .32% of men in the core age cohort in the US were attending law school in 2011. A man of prime law school attending age was 27.3% less likely to be enrolled in law school in 2011 than in 1971.
Assuming 90% of the women attending law school in 1971 were between 22 and 33 years old, there were 7,737 such women. There were about 17 million women in the core age cohort for law school attendance in 1971. Thus approximately .046% of women in the core age cohort in the US were attending law school in 1971. There were about 22.2 million women in the core age cohort for attending law school in 2011. Assuming 90% of women attending law school were in this age group, 61,436 such women were attending law school in 2011. Approximately .28% of women in the core age cohort in the US for law school attendance were attending law school in 2011. A woman of prime law school attending age was 508.7% more likely to be enrolled in law school in 2011 than in 1971.
What this means is that more than 100% of the growth in JD enrollment at ABA law schools over the past 40 years is accounted for by the increasing number of women going to law school. There were 55,063 more JD students at ABA law schools in 2011 than 1971. 59,665 more women were enrolled as JD students in ABA law schools in 2011 than in 1971, while 4,632 fewer men were enrolled as JD students in ABA law schools in 2011 than in 1971.
Holding everything else constant, if the gender ratio between men and women law students had remained the same over the past 40 years there would have been about 86,141 people enrolled as JD students in ABA law schools in 2011, and about 24,498 people would have graduated from those schools. This number of graduates is approximately 12% higher than the total number of new jobs for lawyers (21,880) the BLS estimates will become available on average per year for lawyers between 2010 and 2020.
Clearly, the fact that law schools have produced an enormous oversupply of people with law degrees over the course of the last generation has an extremely significant gender component. These statistics raise all sorts of questions, and in particular this one: To what extent has legal academia's over-expansion depended on the exploitation of the career aspirations of women in particular? Note that there's all sorts of evidence that egalitarian gender practices in regard to law school admissions have had a remarkably muted effect in regard to making law less of a male-dominated profession (For example, 35 years after women started going to law school in numbers not much smaller than men, 85% of the partners and 95% of the managing partners at large law firms are men).
Have law schools managed to expand far beyond the actual economic demand for law degrees in large part because of an always unstated and usually unconscious assumption that comparatively large numbers of women law graduates would drop out of the profession within a few years of graduation? One of the very few longitudinal studies of law graduate career paths suggests strongly this is the case. This study of the University of Virginia Law School class of 1990 found that while, 17 years after graduation, 98.7% of the men who responded to the survey were working full-time, approximately 63% of the women respondents who had had at least one child were not practicing law full-time. (By contrast, there was literally no correlation between the number of children a man had had and the likelihood that he would be employed full-time).
Obviously this is a complex and fraught topic, which for that reason ought to be the subject of much further study.