In 1967 Honeywell, Inc., filed suit against the Sperry Rand Corporation and its subsidiary, Illinois Scientific Developments, Inc., in the U.S. District Court for the District of Minnesota to challenge the defendant's patent claims involving the basic design of the electronic digital computer. The trial opened on July 1, 1971, and lasted 135 days.

Sperry Rand's claims were based on the ENIAC, the first operating electronic digital computer, which had been developed by J. Presper Eckert and John W. Mauchly between 1942 and 1945. The ENIAC, with its 18,000 vacuum tubes, had been commissioned to produce ballistics tables for the Army's Ordnance Department, but it did not have stored memory capability.

Eckert and Mauchly formed the Eckert-Mauchly Computer Corporation in 1946 and began to develop a commercially viable computer using R&D funding from the Census Bureau. This funding proved inadequate, and the company was on the verge of bankruptcy in 1949. Eckert and Mauchly were forced to sell the company to the highest bidder, which was Remington Rand, Inc., a major manufacturer of business machines and office equipment. Remington Rand delivered the first UNIVAC computer to the Census Bureau in March 1951. Under devastating competition from the IBM 650 Computer, introduced in 1954, Remington Rand merged with the Sperry Corporation to form Sperry Rand on June 30, 1955.

The Patent Office finally granted a patent on the ENIAC to Eckert and Mauchly in 1964. Sperry Rand then began notifying all computer companies that they were violating its patent rights and offered to license its competitors for a fee of 1.5 per cent. IBM reached a $10 million settlement with Sperry Rand in 1965. Honeywell and Control Data Corporation rejected Sperry Rand's claim. Sperry Rand sued for patent violation and Honeywell countersued, asserting that the patent was fraudulent.

On October 10, 1973, Judge Earl Larson handed down his decision, upholding Honeywell on every count. He concluded that the ENIAC was derived from a primitive prototype computer developed by John V. Atanasoff and Clifford E. Berry at Iowa State University, even though it had never been fully operational. Damages were not awarded as he found the defendants innocent of willful intent to defraud.