Don Imus has about $40 million left on his contract with CBS Radio. Apparently he'd like to receive that. According to CNN Imus has Martin Garbus, a New York-based attorney at the law firm Davis & Gilbert who is widely recognized as one of the country's most able First Amendment lawyers and the two sides are gearing up for a legal showdown that could turn on how language in his contract that encouraged the radio host to be irreverent and engage in character attacks is interpreted, according to one person who has read the contract.

Don Imus to Sue CBS: $40 Million at Stake

According to CNN, the language, according to this source, was part of a five-year contract that went into effect in 2006 and that paid Imus close to $10 million a year. It stipulates that Imus be given a warning before being fired for doing what he made a career out of - making off-color jokes. The source described it as a "dog has one- bite clause." A lawsuit could be filed within a month, this person predicted.

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CBS boss Les Moonves fired the shock jock on April 12. CBS' lawyers contend Imus was fired for cause and not owed the rest of the money. The re4port also notes that Bo Dietl, a private investigator and author who is a long-time Imus confidante and was a regular guest on the show, has been making the rounds of the cable talk shows defending his friend and had this to say to Fortune:

"I just heard that there is a contract in place, and that he can't be fired without a warning."