Since 1990, while in private practice in Washington, DC, he has been an adjunct professor at Georgetown University's McCourt School of Public Policy.
From April to June 6, 1968, he served as chair of Young Citizens for Kennedy in Connecticut; then he worked with others to collect signatures for hand gun control.
[7] His first book, To a High Court,[8] captured the activist imperative and rough corporate culture that surrounded and tempered him and led to United States of America v. SCRAP, 412 US 669 (1973).
The inauguration, held in Woolsey Hall, included the president of Yale, A. Bartlett Giamatti, and Connecticut Governor Ella T. Grasso.
[19] He has also written articles and a podcast about Giamatti's decision as commissioner of Major League Baseball to banish Pete Rose.
[24] In 1981, Proto returned to Washington, D.C., where he served as general counsel to President Jimmy Carter's Nuclear Safety Oversight Committee (NSOC).
[28] He represented, pro bono, the National Trust for Historic Preservation and Protect Historic America (involving such authors as David McCullough, James Alan McPherson, and Pulitzer Prize-winning journalist Nick Kotz) in their successful effort to stop Disney from building a theme park in Virginia.
[30] His work led, in part, to the publication of his second book, The Rights of My People: Liliuokalani's Enduring Battle with the United States, 1898 to 1917.
In the summer of 2004, he served as counsel to Congresswoman Rosa DeLauro (D-Conn.) in her capacity as chair of the Democratic Party Platform Drafting Committee.
He served as chair (1995–2010) of the American Friends of Wilton Park, a British-American educational organization with origins in World War II.
From 1997 to 2002, Proto undertook an examination of the lives of Bartolomeo Vanzetti and Nicola Sacco and the cultural and legal setting for their 1921 trial and 1927 execution.
In 2002, with the support of Mayor John DeStefano Jr. and Congresswoman Rosa DeLauro, Proto served as chair of New Haven's year-long commemoration of the seventy-fifth anniversary of the execution.
Proto also co-adapted from the original Dutch (with director Tony Giordano) the musical drama, The American Dream: The Story of Sacco and Vanzetti.
[36] In 2016, Proto's one-person play on the 1933 U.S. Senate hearings into the causes of the 1929 stock market crash, The Reckoning: Pecora for the Public, premiered in Seattle.
"[37] Proto's 2020 book, Fearless: A. Bartlett Giamatti and the Battle for Fairness in America, explores the early years of the Italian American professor of Renaissance literature who would later become Yale's first non-Anglo-Saxon president and the commissioner of Major League Baseball.
His interests frequently take him abroad to Royal Geographical Society conferences and events; to the Pacific Northwest for hiking, sailing, kayaking, and snowshoeing; and to the Northeast to maintain close ties with family members and friends.