A study I read a few years back followed Harvard grad lawyers over 15 years. It found a tiny gap in initial pay, less than a percent, due to poorer negotiation, but both male and female graduates were WELL above the media for lawyers, let alone above the median for the population. After graduation, though, it was a steady slide until after the 15 year window concluded, there was over a 40% gap in pay between those female and male lawyers.

But ...

When they accounted for every other factor, including breaks in employment, part time, hours, education maintenance, etc. that dropped to less than 5%. The final nail in the coffin was billables, with male lawyers producing considerably higher billables for their firm. Controlling for that killed the gap. Men and women work differently, with different priorities, even in law.