A professor who was said to have resigned from the New School University when faced with charges of plagiarism has filed a lawsuit alleging he was wrongfully fired and demanding he get his job back.

In a seven-page petition filed in state Supreme Court in Manhattan, Roger Shepherd, who taught in the critical studies department at the university’s Parsons School of Design, claims a memo the school sent to faculty and news outlets in mid-September announcing his resignation was untrue.

In the suit, which names the school and its dean, Paul Goldberger, Mr. Shepherd says that he never resigned, but that Parsons canceled his classes, terminated his pay, and barred him from the Manhattan campus, where he had worked for more than 30 years.

In September, the Chronicle of Higher Education reported that 19 passages from a book by Meredith Clausen, a professor of architecture history at the University of Washington, appeared in a book by Mr. Shepherd without attribution. Mr. Shepherd acknowledged his 2002 book, “Structures of Our Time: 31 Buildings That Changed Modern Life,” lacked attribution in some sections. He told the Chronicle there were “no excuses” and said there were a “variety of reasons” for the error, including pressure after September 11. He also alluded to a mix-up with a research assistant, saying the lifted passages “had been put in as rough stuff and meant to be rewritten.”

Mr. Shepherd’s lawyer, Samuel Landau, also said yesterday there was pressure from the professor’s publisher, Mc-Graw-Hill, to finish the book quickly, and he seemed to downplay the number of passages that were copied.

The petition, filed October 25, alleges that the school knowingly sent out a memo describing Mr. Shepherd’s departure as a resignation when it was actually a termination. Three days after the Chronicle’s story ran, Mr. Goldberger – who is the distinguished architecture critic, now at the New Yorker magazine – and the school’s provost, Arjun Appadurai, sent an e-mail to the school’s staff. “We feel that it is appropriate to be frank about the context for Mr. Shepherd’s resignation since the New School is unconditionally committed to honesty in every feature of its academic life,” the message said.” Mr.Shepherd resigned in light of instances of plagiarism.”

The school released a similar statement a few days later, commending the professor for his years on the job but saying: “We respect and agree with Professor Shepherd’s decision to resign, and we look forward to putting this sad occasion behind us and moving on.”

Mr. Shepherd, who was appointed in 2003 to a five-year full-time faculty position, says the school broke his contract and failed to follow guidelines requiring the provost to convene a committee to review his potential termination. School officials declined to comment on the suit yesterday.