By Dan Whitcomb

(Reuters) - Lawyers for eight gamblers charged with running an illegal sports book are challenging key evidence in the case, saying it was obtained by FBI agents who posed as Internet technicians to gain access to their Las Vegas hotel rooms without a warrant.

If defense attorneys succeed in getting a federal judge to throw out the evidence seized following a raid on the Caesar's Palace hotel rooms, they say they will not only gut the prosecution's case but also establish new limits on how far the government can go in such investigations.

"I'm actually excited as a 35-year practitioner of law to be able to litigate this particular issue. I think it is a truly new area of 4th Amendment law, especially in the electronic age," said David Chesnoff, who represents defendant Wei Seng Phua in the case.

A federal judge in Las Vegas is expected to rule on the motions following a hearing in December and Chesnoff said that if that judge rules the evidence inadmissible, "that's the end of the case."

If he rejects the defense motion and allows prosecutors to use the evidence, a trial will likely begin early next year.

A spokeswoman for the FBI's Las Vegas office referred calls about the case to the U.S. Attorney's Office. A public information officer for that office said on Wednesday she could not comment outside court on a case pending trial.

Wei Seng Phua and seven co-defendants are charged in a U.S. District Court indictment with running an illegal gambling operation out of three luxury villas at Caesar's Palace in June and July of 2014.

In seeking search warrants for the villas, FBI agents asserted that an independent contractor who had been called by the defendants to fix an Internet outage had seen evidence of a sports betting operation.

But attorneys for the defendants, in their motion to have the evidence suppressed, say that the FBI actually disconnected that Internet service, then had agents impersonate computer technicians to get inside and search for evidence.

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"(We) have been unable to find a single time in which any law enforcement agency in the country has ever resorted to using a scheme like this one - terminating a service to a residence in order to deceive the occupants into calling for assistance," the defense attorneys say in their court papers.

"Unsurprisingly, every court to consider anything remotely similar has found it flagrantly unconstitutional," the lawyers say.

(Reporting by Dan Whitcomb; Editing by Eric Walsh)