“The only realistic way to look at this is that it did not stick,” said David Harris, a University of Pittsburgh law professor who has written extensively about police reform and who studied the Pittsburgh experience.

Discovering Section 14141

In 1991, long before cellphone videos, there was Rodney King, an unarmed black man whose beating by four Los Angeles police officers was captured in grainy television footage. The episode led to widespread public outrage and congressional hearings on how to address police misconduct. A tiny provision, known as Section 14141, was inserted into a crime bill signed into law by Mr. Clinton in 1994.

The attorney general was authorized to investigate and sue to eliminate any “pattern or practice” of unconstitutional conduct by law enforcement officers. In the Justice Department, civil rights lawyers wrestled with how, and where, to exercise their new authority.

In Pittsburgh, lawyers had been collecting civilian complaints and learned that over 20 years, only one police officer had been disciplined — one who had an altercation with a black man who happened to be the deputy city solicitor.

In 1995, Pittsburgh had its own Rodney King — Jonny Gammage, a black businessman and cousin of a lineman for the Pittsburgh Steelers, who died of asphyxiation during a struggle with white police officers in the suburbs. Though his death did not involve the Pittsburgh police, it galvanized blacks and whites here to work together, said Tim Stevens, the president of the local chapter of the N.A.A.C.P. at the time.

In March 1996, Witold Walczak, a lawyer for the American Civil Liberties Union, learned about Section 14141 while preparing a class-action suit against the Pittsburgh police. He called the Justice Department and offered up his documents, which led to the federal investigation. The city was offered the chance to avoid a federal lawsuit if it agreed to make certain changes — a consent decree.