You'll get your best answer from a famous case decided by the U.S. Supreme Court in 1991. In that case, the Court allowed a company to copy a local telephone book prepared by another company on the ground that facts are not subject to copyright protection and collections of facts aren't subject to copyright violations unless there is creativity involved in how the facts are arranged.

In the case, which involved a feisty publisher dubbed Feist Publications and a certain Rural Telephone Service Company operating out of Kansas, the Court ruled that merely arranging names alphabetically didn't involve adequate creativity to extend protection to the phone book as a "collection of facts."

It will do you well to read the Feist case. Go to Findlaw (www.findlaw.com), click on the link to the Supreme Court cases, and enter "Feist" in the search box, and voila, you'll see the case.

What all this means for you is that, if your business lists have been amassed with some degree of creativity, you may be be able to claim copyright in them and stop others from verbatim copying. If your lists lack any creative choices, you'll have a much harder time stopping others from copying.