Help, a competitor bought my Web domain!

(FORTUNE Small Business) -- Editor's note: This story was originally published Feb. 12, and is being republished to add additional reporting.

Dear FSB: Both the name and URL of my company's website were registered with a domain name registration company. After more than five years they have sold the URL for my company's name to another person who now runs it in competition to mine. Do I have copyright to this name and URL?

- Garry Whitfield, San Francisco, Calif.

Dear Garry: Unless you have a trademark on the business name, there's little you can do, according to Christine Jones, general counsel for Web hosting company GoDaddy.com, in Scottsdale, Ariz.

"The first thing you have to distinguish is between copyright and trademark. I think the question you need to ask is if you need a trademark to the name and URL," Jones said.

In order to have a trademark, you can either apply to the U.S. Trademark office for a registered trademark - or you could have the trademark simply by being recognized by a name.

"You can get a trademark just by use. If [your business name has] come to be known in the industry with your particular products and services, that's a trademark. It's called a common-law trademark and is just as valuable," said Roni Jacboson, general counsel of New York City-based Register.com.

If your business name and URL are stolen, you can file a domain name dispute under the Uniform Domain Name Dispute Policy, which is governed by the Internet Corporation for Assigned Names and Numbers (ICANN).

A successful challenge must prove that you had a trademark for the name, that you didn't give the person now using your trademarked name permission to use your trademark, and that the user acted in bad faith.

"You would have to prove that the other company does not have legitimate rights or interest in the domain name," Jacobson said. "Bad faith is the bottom line of this whole body of law, because there are legitimate uses."

For example, both a plumbing business and a retail store whose name was "Company" would have legitimate claim to "Company.com."

"Trademark law is about someone investing time and money into building the value of a trademark. If someone else just takes it the next day and sells competitive goods and services, they're trading off the good will of that trademark," Jacboson said.

Furthermore, the history of the parties in dispute can play a factor in which side prevails in a domain name dispute.

"A UDRP panel might look at other activities that the buyer has engaged in - if they do this with a lot of URLs that they're not engaged in, that's a factor," Jacobson said. "It's very, very fact-based. It's not just 'Well, this person is competing with me, therefore they're cybersquatting.'"

If your website's name has not been trademarked, however, and you let the domain name expire, or if the name is considered a generic term, there's little that can be done, according to GoDaddy.com's Jones.

"The domain name registrar has no obligation to continue to hold it for you," Jones said.

You also don't have any real redress with the person who purchased it after you let it expire if they're not using it in bad faith, which would be true even if you did have the name trademarked.

"The lesson to learn is to make sure that you have your name set to auto-renew. Make sure you have a valid credit card number on file with your registrar and make sure you're opening up the e-mail from your registrar," Jones said.

Domain name companies don't make idle threats when telling registrants that their URL registrations are about to expire.

"We really mean it," Jones said. "You have to renew this thing or else it's going to expire."