Bernard N. Katz, 91, a lawyer who spent decades championing labor unions, died at his home in Abington on Saturday morning.

Mr. Katz died of natural causes in his sleep, said his son Michael Katz.

He represented many unions in the city in the 1970s, defending workers in in the manufacturing, industrial, and trade industries. More than 60 years ago, Mr. Katz founded Meranze, Katz and Gaudioso PC, a Center City firm that specializes in labor rights. He practiced until he was 85, licensed in the states of Pennsylvania, New Jersey and New York, before serving as a counsel to the firm. Both Katz’s children, son Michael and daughter Elissa Katz, are partners at the firm.

“If there were a hall of fame for attorneys that represented labor unions, he would’ve been a charter member of that club,” said Harvey Whille, 77, who worked with Katz as president of the Clifton, N.J., local of the United Food and Commercial Workers. "Representing workers was his pride and joy, and he was a pit bull when it came to counseling and navigating us in the right direction.”

Rick Schraeder, 69, former president and business manager of the electrical workers local in Scranton, praised Katz’ dedication.

“He was selfless — you could call him up five times a week, and he’d be there for you,” said Schraeder. “More than an attorney, he often felt like a family member who truly cared what happened. It was clear he felt his work in his heart and soul.”

Mr. Katz, a Philadelphia native, also taught courses in collective bargaining to post-graduate students at Temple University Law School in the 1970s and 1980s. Katz graduated from Temple Law and studied accounting at the university as an undergraduate student. He was an honors student and executive director of the Temple Law Review, formerly known as the Temple Law Quarterly, where he frequently wrote about labor law issues.

He was a mentor to many, from college students to youthful lawyers to countless union leaders.

“He taught me how to use the law to take care of people, and that the love of humanity is equally and if not more important than the law,” said Lynne Fox, who came to work for Katz one year after law school in 1987. “And he was just fun to be around. He had a great sense of humor, and never took himself too seriously.”

In 1970, Mr. Katz served on a commission that created the Pennsylvania Act 195, which gave public employees the right to organize and collectively bargain.

“He was very involved and very passionate about the fight against substandard contractors and the building trades who were destroying area wage and benefit standards,” Michael Katz said.

Mr. Katz grew up in a pro-labor household and was heavily influenced by his own father Phillip Katz, which led to his interest in union worker rights, his daughter said.

After serving in the United States Navy during World War II, Mr. Katz attended Temple Law.

Michael Katz said he thinks serving in the Navy influenced his father’s decision to attend law school. Although Mr. Katz achieved the rank of chief petty officer, he was brought up on charges three times as a result of shore-leave “festivities” at bars with other sailors. He defended himself each time and was found not guilty. Mr. Katz’s community officer later said to him: “If you don’t go to law school on the GI bill when you get out of the Navy, you’re out of your mind. You’re a natural."

Mr. Katz also enjoyed exercising and would frequently travel to Atlantic City to swim in the ocean. “He liked not being confined to edges, like a pool," Elissa Katz said.

Mr. Katz also enjoyed walking on the beach with his wife, Nataleen Katz, and was a regular attendee of Opera Philadelphia shows.

In addition to his wife and two children, Mr. Katz is survived by four grandchildren and three great-grandchildren.

Mr. Katz’s funeral is scheduled for 1 p.m. on Monday at Goldsteins’ Rosenberg’s Raphael-Sacks in Southampton. The burial will take place at Montefiore Cemetery in Jenkintown. Memorial donations can be made to the World Jewish Congress.