In October 2002, credit card giant Visa convinced a Las Vegas federal court to prevent the small business JSL Corp. from using the term “evisa” and the domain “evisa.com” for its website offering travel, foreign language, and other multilingual applications and services. The court ruled that the website “diluted” Visa’s trademark, even though the site uses the word “visa” in its ordinary dictionary definition, not in relation to credit card services. Source: EFF, 3D Tree, Wired.

It seems that Groucho had similar problems.

March 7, 2003 7:30 AM Update

The original link is gone.  (Perhaps the Marx heirs claimed copyright infringement on Groucho’s letter.)

The story goes that while working on the movie “A Night in Casablanca”, the Marx brothers received a letter from Warner Bros. threatening legal action if they did not change the film’s title. Warner Bros. deemed the film’s title too similar to their own Casablanca, released almost five years earlier in 1942. In response Groucho Marx dispatched a very Marxian letter to the studio’s legal department.  There are two links to it below.  Hopefully one will keep working.

Groucho’s Warner Brothers dispute at Chilling Effects
Here it is at The Register (UK)