When Carin Constantine flunked constitutional law after suffering a migraine during the final exam, she did what came naturally. She sued the professor. And the dean. And George Mason University.

"It's very ironic that I am suing my constitutional law professor for a violation of the Constitution," Constantine said yesterday. "How much crazier in life can you get than that?"

Constantine, 36, who has wanted to be a lawyer since junior high school, suffers from intractable migraine syndrome -- headaches so severe, she says, that they nearly blind her. She accused the university of refusing for months to let her retake the exam, then deliberately flunking her after she complained in an article she wrote for the law school newspaper.

Last year, a federal judge in Alexandria threw out Constantine's exercise in the real-life practice of law. But the U.S. Court of Appeals for the 4th Circuit in Richmond decided in her favor Monday, saying Constantine met the requirements to sue under the Americans With Disabilities Act. The appeals court sent her case back to the district court for trial.

A three-judge panel did not rule on Constantine's claim but said that if indeed administrators had denied her a reexamination and a hearing, given her only three days' notice when they allowed her to retake the exam and determined her failing grade in advance, "such conduct would tend to chill a reasonable person's exercise of First Amendment rights." The court acknowledged it was viewing the lawsuit in the light "most favorable" to Constantine.

Constantine, who graduated from George Mason in 2003 with the F on her transcript, is studying to take the bar exam in Florida. She said the whole experience has been "a great lesson in how the system really works."

A spokeswoman for George Mason, Rey Banks, said the university is disappointed in the decision and is reviewing what to do next. "We are at a very preliminary point in this process," said Banks, who would not comment further. George Mason is based in Fairfax; its law school is in Arlington.

The constitutional law professor Constantine sued, Nelson Lund, did not return a telephone call. Neither did Mark F. Grady, who resigned as George Mason law school dean in 2004.

In its 4th Circuit briefs, George Mason argued that Constantine was constitutionally barred from suing the university under the concept of "sovereign immunity" and that some of her "factual assertions . . . are erroneous."

"In taking this position, the University is not saying it should be allowed to engage in unconstitutional discrimination against the disabled with impunity," the briefs said.

Constantine's attorney, Michael J. Beattie, said the decision shows that "public universities are going to have to legally accommodate students with disabilities." Several organizations that support the disabled, along with the U.S. Department of Justice, intervened on Constantine's behalf.

"George Mason's argument was that Ms. Constantine was not qualified to be a law student because she was so severely disabled, so crippled. And that was just offensive," said Beattie, who is blind.

Constantine, a Georgia native who moved to Herndon in 2000, said she began having headaches in high school. By the time she started law school in 2000, she said, a neurologist had diagnosed chronic migraines.

She said the headaches are so disabling that they feel like "someone is sticking a knife in your eyes, like a bomb has gone off inside your head. You get double vision, you get dizzy, you get a halo effect, you get nauseous."

Constantine said that she alerted George Mason to her condition during her second year of law school and that other professors were supportive. But she said Lund gave her a problem from the start, threatening to lower her grade when she was not in class after being hospitalized.

After missing Lund's final exam in December 2002 because of migraines, Constantine was allowed to retake the test in January. About an hour into the exam, she recalled "everything got blurry."

After she flunked the exam, and therefore the course, Constantine pleaded her case with Lund, who said he would talk to the dean. After administrators ignored her calls and e-mails for months, she said, the university set a retest for June but suddenly moved up the date by a month and gave her no time to prepare. She flunked again, had to retake the class with a different professor and wound up getting a C.

Constantine said the 4th Circuit decision is "an amazing step forward for any disabled person who wants to seek a higher education." As for her dream of being a lawyer, she is more determined than ever. She said she might practice disability law.

Carin Constantine suffers migraines.