That same year, Clark was involved in an on-field incident in which he struck Dale Hackbart of the Denver Broncos with a right forearm to the back of Hackbart's head and neck after a play was finished. Hackbart filed a lawsuit and the case eventually went to trial as an intentional tort, specifically battery (tort). Clark testified that his team was losing and that he intentionally hit Hackbart due to his frustration. The case went as far as the United States Court of Appeals (10th Circuit) in 1979.