Had she been prosecuted in state court, Ms. Bond would most likely have faced a sentence of three months to two years, her lawyers say. In federal court, she got six years.

Ms. Bond’s argument on appeal was that Congress did not have the constitutional power to use a chemical weapons treaty to address a matter of a sort routinely handled by state authorities.

She relied on the 10th Amendment, the one so beloved by Tea Party activists. It says that “the powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the states respectively, or to the people.”

A unanimous three-judge panel of the federal appeals court in Philadelphia said Ms. Bond’s argument was a serious one of “first impression.” Then the court ducked answering the question by saying Ms. Bond was not entitled to raise it. Only states, it said, can mount 10th Amendment challenges.

Paul D. Clement, a solicitor general in the administration of President George W. Bush, now represents Ms. Bond. He called the idea that Ms. Bond lacks standing to challenge the law under which she was imprisoned “startling” and “absurd.”

More broadly, Mr. Clement wrote, the Bond case is an instance of an issue that has lately united conservatives, libertarians and liberals. They say there are too many federal crimes, that they are often simultaneously vague and harsh, and that they undermine state authority to maintain public safety.

Mr. Clement said his client’s poisonous rampage was not “successful or particularly sophisticated.”

“Domestic disputes resulting from marital infidelities and culminating in a thumb burn are appropriately handled by local law enforcement authorities,” Mr. Clement wrote. “Ms. Bond’s assault against her husband’s paramour did not involve stockpiling chemical weapons, engaging in chemical warfare” and the like, he added.