Jenner & Block

The firm was founded in Chicago in 1914 as Newman, Poppenhusen & Stern. In late 1928, a former chief justice of the Illinois Supreme Court, Floyd Thompson, joined the firm. Known commonly as "The Judge," Thompson handled several high-profile cases for the firm. Albert E. Jenner, Jr., who served as a former assistant counsel to the Warren Commission, established Jenner & Block's longstanding relationship representing General Dynamics in the 1950s. He later was senior minority counsel on the impeachment inquiry staff for the Republicans on the House Judiciary Committee during the impeachment process against Richard Nixon, but was replaced in July 1974 after advocating for the impeachment of Nixon.

Jenner & Block was one of the first national law firms to establish a Washington practice specifically focused on appeals before the U.S. Supreme Court. A number of lawyers in the Washington office have served as clerks to the US Supreme Court. This office was once headed by Bruce Ennis, Jr., who argued more than a dozen cases before the Supreme Court, including three cases arising under different provisions of the same law, the landmark Telecommunications Act of 1996. The appellate practice was once led by Paul M. Smith. Donald Verrilli Jr., who succeeded Elena Kagan as U.S. solicitor general during the Obama administration, is a former member of the practice.

In 1954, future United States Attorney for the Northern District of Illinois Thomas P. Sullivan joined the firm, and helped establish its pro bono program; Jenner & Block became known as advocates for indigent prisoners facing capital punishment.

Since its founding, the firm has had 10 names. The name of the firm was changed to Raymond Mayer Jenner & Block in 1964 after Samuel W. Block became a name partner. In 1969, it was shortened to its present form.

Targeting by the second Trump administration

Reportedly motivated by personal grievances; actions by the second administration of U.S. President Donald Trump to punish law firms that offered services to the president's perceived political opponents included, on March 25, 2025, President Trump signing an executive order taking action against Jenner & Block. Trump criticized the firm's employment of Andrew Weissmann, who was involved in the Mueller special counsel investigation. On March 28, 2025, the firm sued to stop the executive order, standing out, as some of the other prominent law firms targeted by Trump surrendered to him rather than resist his aggressive campaigns against them. The following day, two district court judges temporarily blocked parts of the executive orders targeting both Jenner & Block and law firm WilmerHale.

Prominent legal work

The firm has a history of litigating and representation in prominent cases, including several argued before the US Supreme Court. The firm's 1985 antitrust lawsuit of AT&T, on behalf of MCI, sowed the seeds for the eventual break-up of telecommunications monopoly in the 1980s.

Pro bono work

In 2005, the firm received the National Coalition to Abolish the Death Penalty's "Legal Service Award" for its work with death row inmates. The New York office is a strong contributor to the firm's commitment to pro bono and public service. A team, along with the Veterans Legal Services Clinic at Yale Law School, successfully represented a proposed nationwide class of Vietnam War veterans suffering from post-traumatic stress disorder who challenged their less-than-honorable discharges from the military. The representation also prompted the Secretary of Defense to issue new guidance to the administrative boards hearing discharge upgrade requests to consider PTSD diagnoses for veterans.

According to annual surveys by The American Lawyer, in 2014 and 2015, Jenner & Block was the leading law firm for per-attorney hours devoted to pro bono work in the US. From 2008 to 2015, it was the leader for five of those seven years.

Recent pro bono victories include the acquittal of Jezon Young and the 2012 acquittal of Calvin Marshall who had been charged with murder.