Gerald Gunther, 75, the author of the standard American law school casebook Constitutional Law who was mentioned as a Supreme Court prospect, died in San Francisco on Tuesday of lung cancer.

Mr. Gunther was born in 1927 in Usingen, Germany, near Frankfurt.

From 1956 to 1962 he was a faculty member at Columbia University School of Law until he was lured away to teach at Stanford, where he was a faculty member the next 40 years.

Mr. Gunther was an expert on the U.S. Supreme Court. A poll issued in 1987 by New York Law Journal ranked him as the "best qualified" choice for appointment to the Supreme Court.