[4] Since ending his work at the NYCLU, Siegel has entered private practice and has represented various activist groups including RodStarz and G1 of Rebel Diaz, Critical Mass, residents fighting the expansion of Columbia University and families against the Rudy Giuliani's 2008 campaign for President of the United States.

In 2010, Siegel negotiated a settlement with New York City, ensuring that online journalists would receive access to official press credentials.

[6] In 2014, Siegel was quoted in the New York Times as saying that his law firm would monitor the cab company SheTaxis for gender discrimination and, if asked, consider filing a claim against them.

A customer is quoted in the article as saying she uses the cab service in order to avoid riding with "intimidating" male drivers, particularly late at night.

[9] In 2015 Siegel joined YAFFED in bringing a lawsuit against 40 yeshivas, private Jewish schools, for inadequate secular studies.