Giles S. Rich, 95, a judge of the U.S. Court of Appeals for the Federal Circuit and a leading authority on intellectual property and patent law, died of lymphoma June 9 at Sibley Memorial Hospital. His decisions helped establish a legal cornerstone for modern biotechnology and the computer, information technology and software industries. He lived in Washington.

Judge Rich had served on the appellate bench since 1956 and at his death was the oldest active federal judge in the nation's history. He achieved that distinction on March 28, 1997. Until his illness, he was said never to have missed a session of his court.

In a letter to Judge Rich in October 1997, William H. Rehnquist, chief justice of the United States, declared, "Every day, you -- like Cal Ripken Jr. [of the Baltimore Orioles] -- extend your record. The nation hails you for your superb service to the judiciary, and so do I."

As a patent lawyer in New York, Judge Rich was one of the key drafters of the Patent Act of 1952, which helped form the foundation of current patent law. When President Dwight D. Eisenhower appointed him to what then was the Court of Customs and Patent Appeals, he was the first patent lawyer to be appointed to that position. When the U.S. Court of Appeals for the Federal Circuit replaced the Court of Customs and Patent Appeals in 1982, Judge Rich was one of 12 founding judges of the new court. He never took senior judge status and a reduced caseload but continued working full time until shortly before his death.

"He is widely regarded as the preeminent patent lawyer, jurist, scholar, student of patent law ever. . . . In his opinions and writings, he took it upon himself to try to educate the bench and the bar in the proper application of patent law," said Donald R. Dunner, a Washington patent lawyer and former law clerk at the Court of Customs and Patent Appeals. "He played a very significant role in the development of that law . . . and he left behind a huge collection of law clerks who were absolutely dedicated to him.

"He loved patent law. He loved his work. I think that's one of the things that kept him alive. His interest never waned. He never got bored. I don't think he had in mind retiring."

Judge Rich was born in Rochester, N.Y. He graduated from Harvard College and Columbia Law School, and he began his professional career in his father's New York law firm when the stock market crashed in 1929.

In the 1940s, he began lecturing on patent law at Columbia Law School, and he became increasingly active in the work of the New York Patent Law Association. In 1950 and 1951, he was president of the New York Patent Law Association.

After his appointment to the Court of Customs and Patent Appeals, Judge Rich was in the position of interpreting and developing the basic patent law that he helped write. In a case involving the patentability of microorganisms, he wrote a decision, later upheld by the Supreme Court, that is widely regarded as having opened the door to the patenting of life forms, permitting the biotechnology industry to thrive. A decision involving the patenting of mathematical algorithms is widely considered one of the legal keystone of the computer, information technologies and software industries.

Before the establishment of the Court of Appeals for the Federal Circuit in 1982, many of the federal district court cases involving patent law were reviewed by the various circuit courts of appeals, resulting in inconsistency and confusion in the application of patent law. The new court, which combined the functions of the U.S. Court of Claims and the Court of Customs and Patent Appeals, was intended to bring uniformity to this process. In addition to patent cases, the court hears appeals from the Court of Federal Claims, the Court of Veterans Appeals, the Board of Contract Appeals and the Merit System Protection Board.

Judge Rich had honorary doctor of law degrees from George Washington University, John Marshall Law School, Franklin Pierce Law Center and George Mason University. He received the Medal of Excellence from the Columbia University School of Law Association.

He was an adjunct professor at Georgetown University Law Center in the 1960s.

His first wife, Gertrude Verity Rich, died in 1953.

Survivors include his wife, Helen Rich; a daughter from his first marriage, Verity Hallinan of Sydney, Australia; and a granddaughter.