He organized the legal defense of Daniel Ellsberg who had released the Pentagon Papers, and he initiated Israel–Palestine talks which eventually brought about the Oslo Accords of 1993.

[6] Sheinbaum eventually discovered that the university was providing cover for an ongoing Central Intelligence Agency operation.

After leaving Michigan State University, Sheinbaum moved to Santa Barbara, California, and became part of a think tank headed by educational philosopher Robert Hutchins called the "Center for the Study of Democratic Institutions".

In 1966 and again in 1968, Sheinbaum ran for the United States Congress in Santa Barbara on a peace platform, but was unsuccessful both times.

[7] In 1971, Sheinbaum was asked by activist "Ping" Ferry to help organize the Daniel Ellsberg Pentagon Papers defense team.

[3] [5] He helped assemble the team of attorneys and became the main fundraiser and spokesperson, raising nearly one million dollars from over 25,000 contributors.

[2][9] Along with the Palestinian Intifada, Sheinbaum assembled a team of Jews to meet with Yasir Arafat to persuade him to disavow terrorism and recognize Israel's right to exist.

[3][10] Anticipating that Arafat would question his credentials, Sheinbaum first held a meeting with then-National Security Advisor of the United States Colin Powell, explaining the situation.