NASCAR suspended Mayfield after he tested positive for methamphetamines during a random drug test, but a federal judge reinstated Mayfield on July 1, noting the likelihood of a false positive in issuing a temporary injunction.

Mayfield has repeatedly denied using the drug and said the positive test resulted from taking the prescription drug Adderall XR, used to treat attention deficit hyperactivity disorder, and a double dosage of the allergy medication Claritin-D. He has also claimed the drug test was flawed.

NASCAR filed an appeal after U.S. District Court Judge Graham Mullen ruled in Mayfield's favor. Mayfield did not compete at Daytona and Chicagoland this month. He was not also on the entry list for this weekend's race at Indianapolis.

"We are pleased with the 4th Circuit Court's ruling to reinstate NASCAR's suspension of Jeremy Mayfield, NASCAR spokesperson Ramsey Poston said in a statement. "This is an important decision for NASCAR to make fair and equitable regulations for the safety of competitors and spectators at the track. We will continue to respectfully make our case for as long as the litigation continues."

Mayfield became the first driver to be suspended indefinitely since NASCAR's revised drug policy went into effect earlier this year.