Daniel Riess handled many cases as a patent attorney for nearly 50 years, but by far his best-known work was when he represented the Keebler Co. in what came to be known as the "soft cookie wars."

Procter & Gamble Co. alleged Keebler and two other cookie-makers, Frito-Lay and Nabisco Brands, infringed P&G's 1984 patent on "dual-textured cookies," which were crisp outside and soft and chewy inside. P&G marketed the cookies under its Duncan Hines brand; Keebler's version is called Soft Batch.

Riess and many other lawyers spent years on the case until the suits were settled in September 1989, with Keebler and the other two companies paying P&G $125 million.

John Alex, a partner in what is now the Cook Alex law firm, called it "one of the most major patent cases of all time."

Riess, 80, died of congestive heart failure Oct. 12 at Northwestern Medicine Lake ForestHospital, according to his daughter Dana Riess. He had lived in Lake Forest for nearly 40 years.

Riess was born and grew up in Evanston. After graduating from since-closed St. George High School in the north suburb, he went on to Northwestern University in a five-year program in engineering that included work in industry. He graduated with a bachelor of science degree in chemical engineering in 1959.

He went to school on a Navy scholarship, and upon graduation was commissioned as an officer and served on active duty in the destroyer and submarine forces for four years in the Pacific. After completing active service, he continued with the Naval Reserve, which included command of two submarine reserve training divisions in Chicago. He retired from the Naval Reserve as a captain after 23 years.

After leaving active duty, Riess attended Georgetown University Law Center in Washington part time while working as a patent examiner at the U.S. Patent and Trademark Office in chemical engineering.

After graduating from Georgetown Law in 1967, Riess joined the law firm of what is now Banner & Witcoff in Chicago, specializing in intellectual property law matters. From there, he moved to Cook Alex in the early 1980s.

The cookie wars case got underway not long after. Although it took a great deal of his time and energy, the case had its benefits for Riess, his daughter said.

"I know my dad really enjoyed working on the case," Dana Riess said. "He used to joke that Keebler paid for our college."

As reported at the time of the September 1989 settlements, lawyers preparing for a trial scheduled to begin in early October took 120,000 pages of testimony from 200 witnesses over 2 1/2 years. Arrangements had been made to remove half the spectator seats in the courtroom to accommodate file cabinets holding 10,000 exhibits.

The case had elements of intrigue in the form of charges of industrial espionage that included P&G accusing Keebler of trying to gather trade secrets by flying a small plane over a P&G cookie-making plant under construction and accusing a representative of another defendant company of posing as a customer to gain access to a confidential sales meeting.

Under the settlements, the three rivals were prohibited from infringing on P&G's patent in the future. It was reported that all three competitors, however, had devised new formulas after the suits were filed.

Like Keebler, Nabisco paid $52.9 million of the settlement, with Frito-Lay paying $19.1 million.

Dana Riess, who was in high school at the time of the case, said it was both fun and interesting to go into grocery stores then to see what cookies were on the shelves. "But to this day," she said, "my preference is really for crunchy cookies."

Daniel Riess was a partner for over 25 years at Cook Alex before retiring in 2014.

He served on the library board in Buffalo Grove when he lived there. In Lake Forest, he was a director of the Lake Forest Preservation Foundation.

He is also survived by his wife, Patricia; another daughter, Alison; and a granddaughter.

Services were held.