He began his career with the Philadelphia Industrial Development Corp. and in 1964 joined the law firm of Morgan, Lewis & Bockius. He became a partner in 1970.
In the 1980s, Mr. Zimmerman joined the law firm Blank Rome L.L.P. as a partner. He resigned in the 1990s to form a solo practice. He never retired.
Mr. Zimmerman loved the law, but his true passion was music. He asked for piano lessons for his 10th birthday, and never stopped playing or improving.
Also a precocious clarinet player, he was a member of the Philadelphia Musicians' Union by the seventh grade, playing professionally with Pottsville's Third Brigade Band.
In high school, he played first clarinet in the Pennsylvania All-State Band, and in college, he played with the Smith College Orchestra. Later, he performed with the Symphony Club of Philadelphia. He attended Philadelphia Chamber Music Society concerts and was a board member of Tempesta di Mare, which performs baroque music.
Throughout his life, Mr. Zimmerman modeled for his family the practice of patient, lifelong study. He could draw beautifully and studied faces.
"He loved to sketch faces, and many who attended work or board meetings, and have interesting bone structure, found themselves [depicted] in a margin of his legal pads," his family said.
As a boy, baseball was his sport, although he enjoyed following Pottsville football. Later, he became devoted to the Phillies and Eagles. As an adult, he played tennis and sailed on the Sassafras River on Maryland's Eastern Shore.
He served on the boards of nonprofit historical societies, musical groups, and civic associations. One - the Bala Cynwyd Neighborhood Club - named him citizen of the year in 2014.
Mr. Zimmerman's life was centered on work, his hobbies, and his family. "He also loved corned beef, martinis, Philadelphia, travel, his teams' victories, a beautiful phrase, and a great question," his relatives said.
He was married to Juliet J. Goodfriend before they divorced. She survives.
He is survived by his wife, Judith Zetzel Nathanson; a daughter, Erica J.; a son, J. Micah; four grandchildren; a brother; stepsons Gabriel and Will Nathanson; four step-grandchildren; and two nieces.
Services were Wednesday, Aug. 13.