You can’t always get what you want, and sometimes just wanting can be problematic.

Facebook was sued in federal court on Friday for its recent launch of a “Want” button – a feature that lets users create wish lists of products by clicking a button that appears beside the products online.

Facebook recently announced that it was testing the new feature on the websites of several online retailers, including Pottery Barn, Nieman Marcus, and Victoria’s Secret.  Facebook is also trying out a “Collect” button and the familiar “Like” button to see which of the three draws more clicks.

But a Michigan company called CVG-SAB, LLC claims that it has marketed and used a “Want” button in essentially the same way since September 2010.  The company, which operates the websites wantbutton.com and wanttt.com, also owns several U.S. trademark registrations, and even more pending applications, for the term “WANT” when used in this context.

On October 12, CVB-SAB filed its complaint in the U.S. District Court for the Eastern District of Michigan, alleging trademark infringement, unfair competition, and violations of the Lanham Act, the Michigan Consumer Protection Act, and Michigan common law.  The company has sought an injunction against Facebook’s use of the “Want” button as well as damages.

According to the complaint, the plaintiff’s customers include Tommy Bahama, Burlington Coat Factory, Sharper Image, and Frederic’s of Hollywood.  On these retailers’ sites, a small button containing the word “Want” and a price tag icon appears near a product’s description.

Interestingly, the “Want” button on these sites, when clicked, launches a new window that invites the user to install the “WANT Button” app on Facebook.  According to its description, the app allows users to “Keep track of the products you Want from anywhere on the web in one convenient location on Facebook.”

In other words, the plaintiff’s “Want” button is already integrated with Facebook as a Facebook-approved app.  To further muddy the waters, the “WANT Button” app describes itself as “The ‘Like’ Button for Shopping” – a clear reference to Facebook’s ubiquitous “Like” button, for which Facebook has sought trademark protection.

Facebook has yet to respond to the complaint, but the company may argue that “WANT” is, at most, merely descriptive of the button’s function and has not acquired the secondary meaning that is needed to afford trademark protection.

Because Facebook has filed several applications for its LIKE mark, Facebook probably would not want to take the position that “WANT” is generic and incapable of trademark protection; such an argument would seem to undercut Facebook’s own position on LIKE.