Responding to a wrongful termination lawsuit filed in August by a former first-year associate fired after eight months on the job, Kasowitz Benson Torres & Friedman argues that the suit should be dismissed because the plaintiff signed a separation agreement with the firm in exchange for severance pay and other benefits and gave up his right to sue as part of that agreement.

The firm lays out its case for tossing Gregory Berry’s suit in a 22-page response to Berry v. Kasowitz, Benson, Torres & Friedman, 5652274/2011, filed Wednesday in state court in Manhattan. Joseph Piesco, Jr., an employment litigation partner at Kasowitz, is representing the firm and partners Aaron Marks and Kim Conroy. Mr. Berry claims that Mr. Marks and Ms. Conroy conspired to have him fired.

News of Kasowitz’s response to Mr. Berry’s claims was first reported by Above the Law.

In his suit, Mr. Berry, who is representing himself, accuses the firm of negligent misrepresentation, wrongful termination, breach of employment contract, and intentional infliction of emotional distress, among other things. He seeks $2.55 million in estimated income he says he lost as a result of being fired, as well $75 million in compensatory and punitive damages.

Mr. Berry—who, according to his complaint, worked as a software engineer and entrepreneur in San Francisco for 15 years before switching careers—claims he was fired after being reprimanded for refusing to help Ms. Conroy with document review and, later, sending an e-mail to a dozen partners asking for projects to manage.

In the e-mail, reproduced in his complaint, Mr. Berry argued that his past experience made him more valuable than the usual first-year associate and that “after working here for several months now it has become clear that I have as much experience and ability as an associate many years my senior, as much skill writing, and a superior legal mind to most I have met.”

In rebutting Mr. Berry’s claims, Kasowitz’s main argument is straightforward: advised by an employment attorney, Ethan Brecher of Liddle & Robinson, Mr. Berry was offered and accepted a separation package that included two months’ salary, accumulated benefits, and two months’ access to his firm e-mail and telephone—and barred him from suing the firm.

As to Mr. Berry’s claims that he was fired for complaining about the tasks he was given and asking for more challenging assignments, Kasowitz maintains that as an “at will” employee he is barred by New York state law from making the tortious interference and conspiracy claims he asserts in connection with those allegations.

Mr. Berry also claims that Kasowitz violated the severance agreement by yanking his e-mail and phone access days after both parties signed the agreement. In its response, the firm says it terminated Mr. Berry’s e-mail access after discovering that he had misappropriated 190 electronic documents and files with sensitive client information.

In its Wednesday filing, Kasowitz also responds to Mr. Berry’s claim that the firm misrepresented the nature of associate work on its website.

In his complaint, Mr. Berry says he decided to join Kasowtiz in part based on unspecified promotional materials describing it as an “exciting firm that valued creativity and intelligence and ambition and allowed associates to grow as quickly as they could” and saying that “document review was a burden shared by all, and that junior associates were encouraged to seek out more interesting assignments.”

The firm responded that even if such statements were made, each one was “at most a statement of opinion.”

Mr. Berry, who says on his website that his practice focuses on complex commercial litigation, IP, employment, insurance recovery and bankruptcy, did not immediately return a call seeking comment. On his site, Mr. Berry says he left Kasowitz after discovering that its emphasis on generating billable hours left him “wasting his talents.”