The popular rock band joins dozens of advertisers in distancing themselves from Rush Limbaugh. Plus: What the radio host has in common with an Illinois congressman.

Radio show host and political provocateur Rush Limbaugh is now facing an attack on a new front over his "slut" comment about Georgetown student Sandra Fluke.

As if the increasing number of advertisers pulling out from his show isn't enough trouble, Limbaugh also has been served with a cease-and-desist letter from Rush, the Canadian trio with 24 gold albums whose classic rock staples include "Tom Sawyer" and "The Spirit of Radio." The band demands that Limbaugh stop using their recorded music during his radio show and are threatening the conservative commentator with a lawsuit for copyright and trademark infringement.

Radio programs generally don't need explicit permission from songwriters to play their music. Instead, most radio stations pay flat fees to performance rights organizations such as ASCAP, BMI, or SESAC for blanket licenses.

But in the band's cease-and-desist letter (below), it's being claimed that the "public performance of Rush's music is not licensed for political purposes."

It's a somewhat similar argument that many musicians have made when taking on politicians who have used songs at campaign rallies. For instance, Newt Gingrich is currently being sued for playing Survivor's 1982 hit "Eye of the Tiger" at a campaign rally. Essentially, these musicians are attempting to argue that the scope of a public performance license has limits.

But Rush's thinking in this latest Limbaugh dispute is raising skepticism, even among musician-friendly attorneys.

Lawrence Iser, a lawyer who represented Jackson Browne against John McCain and David Byrne against Charlie Crist, believes that Limbaugh's radio stations likely have a blanket performance licenses with SESAC, which is affiliated with Rush's music publisher, and that the license should cover use of the band's songs.

"Radio broadcast is the quintessential 'public performance,' ” he says. "Even if this were a 'political broadcast' as alleged in the letter -- and Limbaugh is, of course, an entertainer, not a politician -- I'm not aware that there is a 'political use' exception to the public-performance license."

The dispute also raises other issues because of the "Rush" connection.

The band asserts that when Limbaugh plays their music, he's infringing their trademarks and implying an endorsement. This isn't the first time that something like this has popped up as a controversy. When Illinois Republican Joe Walsh was running for his congressional seat, he used the James Gang song "Walk Away," which prompted an objection from an attorney for the songwriter — Eagles guitarist Joe Walsh — who claimed the public might be led to believe "that Joe is endorsing your campaign, or, God forbid, you."

It should also be noted that Rush -- the band -- takes its trademarks seriously enough to pursue action when cease-and-desist threats are ignored.

The musicians are involved in a tug-of-war at the U.S. Trademark Office with a Florida-based clothing company called "Rush Couture" over a series of series of T-shirts with phrases like "Crystal Rush" and "Spirit of Rush Couture." In a notice of opposition, the band notes its international fame and success, including a star on the Hollywood Walk of Fame. Two weeks ago, the clothing company answered the opposition by saying the term "Rush" is "highly diluted," adding that there could be no likelihood of confusion among the public.

The band, like many advertisers, now doesn't want to take any chances that people will believe there's any endorsement of a controversial radio host and his political views. Regardless of the ultimate legal merits of Rush's claims, here's the cease-and-desist letter that was first published at The Huffington Post:

Ladies & Gentlemen: I am the attorney for Rush, their management company, S.R.O. Management Inc., their music publishing company, Core Music Publishing and their record company, The Anthem Entertainment Group Inc. According to media reports, Rush Limbaugh, Premiere Radio Networks and The Rush Limbaugh Show have been using Rush's recorded music as part of what is essentially a political broadcast. The use of Rush's music in this way is an infringement of Rush's copyrights and trademarks. The public performance of Rush's music is not licensed for political purposes and any such use is in breach of public performance licenses and constitutes copyright infringement. There are civil and criminal remedies for copyright infringement, including statutory damages and fines. (see sections 501-513 of Title 17 of the United States Code http://www.copyright.gov/title17/92chap5.html) In addition, the use of Rush's music in this manner implies an endorsement of the views expressed and products advertised on the show, and is in breach of not only copyright and trademark rights, but also, of section 51 of the New York Civil Rights Law (excerpt attached). Accordingly, we hereby demand that you immediately stop all use of Rush's music and confirm that you will do so. Yours very truly, Robert A. Farmer Director of Legal Affairs S.R.O. Management Inc., Core Music Publishing The Anthem Entertainment Group Inc.

E-mail: eriqgardner@yahoo.com

Twitter: @eriqgardner