Mr. Kerpelman, who was considered a gadfly by some and a tireless advocate of the downtrodden by others, spent much of his career as an advocate for difficult and unpopular causes. Before he was disbarred in 1989, he worked to help preserve wetlands on Maryland’s Eastern Shore and to promote the legal rights of divorced fathers.
In recent years, Mr. Kerpelman was an advocate for open government, often filming governmental meetings for broadcast on public-access television. He was credited with opening the doors of meetings of Baltimore’s Board of Estimates, in which the mayor, city council president, comptroller and other officials discuss the city’s fiscal policies.
“Some found him irascible and cantankerous,” Maryland Gov. Martin O’Malley (D) said Saturday in an interview. “He would show up at the Board of Estimates meetings and quote the open meetings law, then pull out his video camera.
“He appeared to me to be a relentless and principled advocate. I admired the fearlessness and the nonchalant courage with which he took on authority and convention.”
Mr. Kerpelman’s most famous legal case began in 1960, when he took on O’Hair as a pro bono client. O’Hair’s son, William J. Murray III, was a student at a Baltimore junior high school, which required daily recitations of Bible verses and the Lord’s Prayer.
Even though individual students could be excused at their parents’ request, Mr. Kerpelman argued that the schools had no right to impose prayers on children. The Maryland Court of Appeals, the state’s highest court, disagreed, ruling to preserve the religious readings.
Mr. Kerpelman appealed to the U.S. Supreme Court on First Amendment grounds, arguing that the Constitution prohibited the establishment of a state religion. The Baltimore case was joined with a similar one from Pennsylvania, Abington v. Schempp, and the joint school-prayer case became generally known by that name.
In his argument before the Supreme Court, Mr. Kerpelman addressed the coercive nature of the religious readings in public schools. Children whose views differed from those of their classmates, he said, were often subjected to cruelty and retribution.
“This boy,” he said, referring to O’Hair’s son, “was spat upon, insulted, actually assaulted.”
Lawyers for the school districts argued that the religious recitations were intended to instill “moral values,” but that point was rejected by the Supreme Court. By an 8 to 1 decision, the court banned the use of prayer and sectarian ceremonies in the nation’s public schools.
“They are religious exercises, required by the states in violation of the command of the First Amendment that the government maintain strict neutrality, neither aiding nor opposing religion,” Justice Tom C. Clark wrote in the majority opinion. “In the relationship between man and religion, the state is firmly committed to a position of neutrality.”
Mr. Kerpelman often pointed out that private prayers by students and nonsectarian moments of silence remained perfectly legal. But the Supreme Court’s decision was deeply unpopular with certain sectors of the public and remains a touchstone of the conservative movement to this day.
After the case was resolved, Mr. Kerpelman had few dealings with O’Hair, who left Baltimore in 1964 and disappeared in 1995. Her mutilated remains, along with those of a son and granddaughter, were identified in a remote part of Texas in 2001.
William Murray, the son involved in the Supreme Court case, became a Christian evangelist and an advocate of restoring prayer to public schools.
Leonard Jules Kerpelman was born Jan. 12, 1925, in Baltimore. Both of his parents were lawyers. He was blind in one eye and had polio as a child, leaving him with only partial use of his left arm.
He received a bachelor’s degree in chemical engineering from Johns Hopkins University in 1945 and a law degree from the University of Maryland in 1949.
Mr. Kerpelman handled environmental and free-speech cases throughout his career and was known as something of an eccentric. He often commuted to his office on a bicycle and, in the mid-1960s, bought a 1948 Cadillac limousine as a family car.
“He drove it till it wouldn’t drive anymore,” Jason Kerpelman said. “The odometer stopped at 257,000 miles, and he drove it for a number of years after that.”
After serving on legal assistance committees of the NAACP, Mr. Kerpelman publicly broke with the civil rights group in 1965, when riots broke out in the Watts neighborhood of Los Angeles.
“The Watts riots disgusted me and sickened me as a human being,” he wrote in a letter to the Baltimore Evening Sun. He believed NAACP leaders were condoning violence and concluded: “I am opposed to any further extension of civil rights to Negro citizens, no matter that they may be entitled to them.”
In the 1970s, Mr. Kerpelman took on many cases involving the custody rights of divorced fathers. He helped organize Fathers United for Equal Rights, and his outspoken advocacy led to many battles in and out of the courtroom. He was suspended from practicing law for three years in the early 1980s.
During a child-abduction trial in Montgomery County in 1987, Mr. Kerpelman was sentenced to five days in jail for contempt of court.
His behavior, the judge wrote, “was so obnoxious that the dignity of the court and the orderly administration of justice was castrated.”
In 1989, the Maryland Court of Appeals disbarred Mr. Kerpelman for disruptive behavior and overcharging his clients.
Survivors include his wife of 63 years, Elinor Hoffman Kerpelman of Baltimore; four children, Antonia K. Fowler of Reisterstown, Md., Jason Kerpelman of Catonsville, Md., Saul Kerpelman of Baltimore and Sally A. Semyonova of Amsterdam; three brothers, Charles Kerpelman of Geneva, Larry Kerpelman of Acton, Mass., and William Kerpelman of Rockville; a sister, Marjorie Auerbach of Silver Spring; and eight grandchildren.
In 1963, soon after the Supreme Court decision outlawing official prayer in schools, Mr. Kerpelman answered his many critics with a letter published in The Washington Post.
“Those whose letters contained threats of physical violence: Please contact my secretary for an appointment,” he wrote. “There is a considerable waiting list.
“Those who called me a Communist: It must have been someone who looks like me, whom you met at a cell meeting.
“Those whose letters consisted principally of obscenity: I am all innocence and did not get your message.
“Those whose letters mixed obscenity with Biblical quotations: Are you all right?
“Those who expressed fear for my immortal soul: Don’t worry yourselves. I have been a lawyer too long to be eligible for salvation anyway, though when I arrive at the celestial conference on the matter, I think I may be able to talk myself out of whatever difficulties I am in at the time.”