That's the title of this article by Katelyn Polantz. The survey says that big private law firms have the greatest disparities, and with smaller private firms have smaller disparities, with men making more than women in both settings. But there's this:
Public interest law and solo practices were the only job settings where the median income for women, at $90,000 in public interest and $65,000 in solo, outpaced men, at $70,000 and $60,000, respectively.
So, it's not just that public-interest lawyers have way more fun.