GREELEY, Colo. -- Invoking Thomas Jefferson and Mr. Hankey from the television series "South Park," the lawyer for an ex-professor accused of leaving dog feces at a congresswoman's office said her client's actions qualify as protected speech under the First Amendment.

Kathleen Ensz faces a misdemeanor charge of "use of a noxious substance." She is accused of taking dog feces from her backyard, wrapping it in a political mailer from Rep. Marilyn Musgrave, and leaving it at the Republican's office, according to court documents.

Ensz, a Democrat, was angered by repeatedly receiving mailings from Musgrave, the documents said.

"What she did was probably crude and boorish," Patricia Bangert, one of Ensz's attorneys, argued during a hearing Tuesday, when she likened the conduct to a form of political protest such as Jefferson's criticism of the King of England.

Bangert held up Mr. Hankey, an animated, talking piece of human excrement from "South Park," as evidence of how commonplace feces is for expressing disdain.

"Etiquette and propriety aside, it is commonplace in today's society to equate a distasteful or disliked person, situation or thing, to feces," Bangert said.

Ensz, 63, a retired professor emeritus from the University of Northern Colorado, was scheduled for trial in Weld County on May 15.

Ensz began teaching at UNC in 1970 and earned her emeritus status in 2000. Since she is no longer on staff, she doesn't face sanctions, said UNC spokeswoman Gloria Reynolds last May.

Musgrave's spokesman Aaron Johnson said, "Right now, this issue is between Ms. Ensz and law enforcement officials."

At the time of the incident last May, Musgrave's camp claimed the gesture was a political dirty trick and demanded an apology from Musgrave's likely Democratic opponent, state Rep. Angela Paccione of Fort Collins, who went on to lose the election to the incumbent.

Paccione's campaign denied any involvement.

The package was traced to Ensz by a postal service bar code on the box. It allowed a police officer to trace the package to Ensz's neighborhood and further investigation led to the retired professor.