In federal court papers, NASCAR accused Mayfield of breaching his contract, and of defrauding NASCAR and its competitors of earnings.
"He competed in a number of races that, had we known that he'd been on the medication he was on, and certainly known there was in illegal substance involved, we wouldn't have allowed him to compete," NASCAR spokesman Ramsey Poston said at Pocono Raceway. "In effect, he took money away from other potential competitors that could have gained those earnings."
Mayfield was suspended May 9 for failing a random drug test conducted eight days earlier at Richmond International Raceway. His suspension applies to both his role as driver and owner of the No. 41 Toyota for Mayfield Motorsports.
NASCAR had moved Mayfield's challenge of his indefinite suspension to federal court earlier this week, keeping the driver out of his car for another week.
On Friday, NASCAR's counterclaim said Mayfield's willful misconduct at the racetrack by competing while an illegal substance was still in his system is evidence that he presented a danger to himself and others.
Poston said no hearing date has been set.
Mayfield's attorneys said last week in court that the driver tested positive for amphetamines, which they attributed to the use of Adderall for Attention Deficit Hyperactivity Disorder and Claritin-D for allergies.
But NASCAR attorney Paul Hendrick said in court that three drugs were found in Mayfield's system, and the Adderall and Claritin-D were accounted for in the results. He described the third as a "dangerous, illegal, banned" substance, but did not name it.
David Black, the administrator of NASCAR's drug-testing program, has repeatedly rejected Mayfield's explanation.
"Dr. Black and his team will work with competitors on prescribed medicine," Poston said. "We do that quite often on a case-by-case basis. The policy is the misuse or abuse of any drug is a violation of the policy."