CHARLOTTE, N.C. -- Charles Yesalis foreshadowed months ago what happened Wednesday when a federal judge lifted NASCAR's suspension of Jeremy Mayfield for a positive drug test.

Yesalis, one of the country's leading authorities on performance-enhancing drugs, blasted NASCAR in September when series officials revealed their updated policy.

There was no list of banned substances -- unlike any other pro sports league Yesalis was aware of.

"This is really bad," Yesalis told The Roanoke Times last fall. "If I were a driver and got caught, I'd hire me a real big-time lawyer and say: "Make mincemeat of it.'"

Mayfield, who claims his positive test for methamphetamine is a result of two medicines he took before a random drug test last month, did just that. Judge Graham Mullen's injunction Wednesday gives Mayfield a chance to drive in Saturday's Coke Zero 400 at Daytona International Speedway.

Concluding the "likelihood of a false positive in this case is quite substantial," Mullen ruled in Mayfield's favor after about two hours of arguments, including NASCAR's contention that Mayfield is a danger to the sport after testing positive for high amounts of a dangerous, illegal drug.

Daytona would be Mayfield's first event since being indefinitely suspended on May 9.

"This is huge for us," Mayfield said. "This means more to me probably than any race I've ever won or anything."

NASCAR had not determined Wednesday night if it would appeal the decision.

To address NASCAR's concerns of allowing someone who tested positive for an illegal drug back on the track, Mullen said NASCAR can test Mayfield constantly and ask for a hair sample "to determine if he's been a meth-head or not."

"If they want it, I cut it about once a week so we can do that," Mayfield said. "Whatever we've got to do."

As Mayfield celebrated the decision, questions about the effectiveness of NASCAR's Substance Abuse Policy persist.

It was clear that Mullen had his doubts about the policy, based on how he challenged NASCAR's lawyers during the proceedings.

Mullen questioned how NASCAR determines what violates the policy without a list of banned substances and what kind of an appeal process there is.

Series officials fended off questions last fall about not having a list of banned substances. They stated that the series had the toughest drug policy in all sports, since anyone could be penalized for the "misuse or abuse of any drug."

That approach didn't work Wednesday.

Mullen asked Helen Maher, an attorney for NASCAR, if there was a limit to NASCAR's discretion on what violates the policy. Maher's indirect answer caused Muller to interrupt her with a stern voice.

"That's not a response," Mullen said. "If your answer is none, step up and own it."

Maher said: "It's always up to NASCAR's sole discretion."

Yesalis said Wednesday that the solution is simple.

"For crying out loud, you can still do a list," he said, referring to a list of banned substances. "They could put together a group of experts ... [and] do a "Thou Shall Not" list."

Yesalis, who has testified before Congressional hearings on performance-enhancing drugs, says that other leagues that list banned substances include a clause "and related substances" to keep up with the growing types of drugs used.

Mullen's questions Wednesday didn't end with Maher. The judge asked Paul Hendrick, another attorney for NASCAR, about an appeal process with the policy.

"How does Mr. Mayfield contest a false positive? What is the remedy?" he asked.

Hendrick said: "There is no remedy to contest a false positive until he sees the testing results."

A NASCAR official said when it indefinitely suspended Mayfield in May that the penalty could not be appealed. Essentially, the only appeal was testing a second sample of Mayfield's specimen.

When a driver provides a urine sample, it is divided into two. One sample is tested and the other is stored in case there's a dispute.

Mayfield's lawyers challenged the procedure and stated that the lab tested the second sample without Mayfield's consent, impacting the appeal process. Again, it was a case of the policy not being specific enough and leaving questions for a judge to decide.

Mayfield's attorney Bill Diehl also argued the test results would only be accurate if Mayfield were a habitual meth user. If Mayfield used the drug at the levels the NASCAR test indicated, Diehl suggested Mayfield would be "either a walking zombie or he's dead."

"His teeth were never rotting out, his eyes were not sunken," Diehl said. "He never displayed any characteristics that are commonly seen by everyone among people who use meth."

Such questions with the policy benefited Mayfield.

Diehl, whose flowing, long, yellow hair adds to his flair for the dramatics, implored Mullen that he had to issue an injunction.

"It's July 4th weekend," Diehl said in court. "Somehow that rings true as I talk to you and ask you to correct a wrong.

"Independence Day for Jeremy ought to be today."

It was, but this case is far from complete.

"This is only a temporary injunction, the legal case continues beyond this point," NASCAR spokesman Ramsey Poston said. "We will continue to make our case."

As long as questions remain, NASCAR's task becomes more difficult.

The Associated Press contributed to this report