[specify] After law school, Green returned to Washington, D.C., and ran the Congress Watch division of the consumer rights advocacy group Public Citizen from 1977 to 1980.

[3] In 1981, Green and songwriter Harry Chapin founded the New Democracy Project, a public policy institute in New York City.

"[10] His opinion mirrored the stance of Common Cause, the citizens' lobby that organized to abolish PACs over fears of "special interests" buying votes.

A 1994 investigation on the Bell Regulations ("Libby Zion Law") to limit resident working hours and requiring physician supervision and a follow-up study prompted the New York State Department of Health to crack down on hospitals.

He wrote laws that matched small donations with multiple city funds, created the Voter Commission, upheld the legality of the Independent Budget Office, barred stores from charging women more than men for the same services, and prohibited companies from firing female employees merely because they were victims of domestic violence.

One of Green's highest-profile accomplishments was a lawsuit to obtain information about racial profiling in Rudy Giuliani's police force.

In the 2000 campaign, Green praised Nader's work as a consumer advocate but endorsed Democratic nominee Al Gore, who narrowly lost the election to George W.

[12] The Economist wrote, "The billionaire businessman [Bloomberg] is usually seen as one of the post–September 11th winners (if such a word can be so used): he would probably have lost the mayoralty to Mark Green, a leftish Democrat, had the terrorist strike not happened.

Yet it is also worth noting that his election probably spared New York City a turbulent period of score-settling over Rudy Giuliani's legacy.

"[13] Chris Smith wrote in New York Magazine in 2011, "Many old-school Democrats believe that Bloomberg's 2001 victory over Mark Green was a terrorist-provoked, money-soaked aberration.

An investigation by the district attorney of Kings County, New York, Charles J. Hynes, came to the conclusion that "Mark Green had no knowledge of these events, and that when he learned of them, he repeatedly denounced the distribution of this literature and sought to find out who had engaged in it.

"[15] The incident kept Ferrer from endorsing Green and is thought to have diminished minority turnout in the general election, which helped Bloomberg win in an overwhelmingly Democratic city.

[citation needed] On September 12, 2006, Green lost to Andrew Cuomo in his bid to secure the Democratic nomination to succeed then-Attorney General Eliot Spitzer.

[19][20][21] As one of the top two finishers in the Democratic primary, Green qualified for the September 29 runoff, but lost to City Councilmember Bill de Blasio who went on to win the mayoralty in 2013.

Green has appeared on these slates: He was a regular guest on Crossfire on CNN, and also on William F. Buckley's Firing Line, Inside City Hall on NY1, and Hardball with Chris Matthews on MSNBC.

[25] On February 27, 2017, Green founded and ran the Twitter handle @ShadowingTrump [see ShadowingTrump.org] "to daily debunk Trump and propose progressive alternatives."