An important part of trademark law is whether two marks are confusingly similar to customers. This issue is frequently the key dispute in a trademark infringement case. If you believe somebody has copied your mark, or if somebody has accused you of copying their mark, you will want to meet with a trademark lawyer to determine the best way to protect your mark.

It's important understand what "confusingly similar" means, so that when you see another mark just like yours, or close enough, you will be able to look at it critically. Note that trademark law applies equally to service marks, so these guidelines will still be helpful; just substitute in the word "service" for "product" or "item." The issue is whether there is a "likelihood of confusion." This means that customers will probably be confused between the two marks.

Infringement Factors

The following checklist is meant to help you determine whether your trademark may have been infringed.

• Is it likely that a customer will buy a product, believing he or she is buying somebody else's product?
• Are the products the same kind of item?
• Is it likely that a customer will believe that a particular entity has sponsored or approved the item bearing the mark?
• Are the two entities using the mark competing with each other for business?
• Do the two entities sell their product in the same sorts of stores?
• Do the two entities sell their product to the same kind of customers?
• How much do the two products cost? (This is a good way to determine whether a product is a knock-off as well.)
• How do the two entities advertise and inform customers about their products? Are they doing similar marketing?
• Does one entity use the same mark on several different kinds of products?
• Are the two products closely related? This question might arise in a situation like the following example: one entity using the mark sells cosmetics and the other entity sells hair do-dads. Both products are be found in the "Health and Beauty" department of a drug store or discount store, sometimes in the same aisle. Even if the products are different, they are closely related. But if one entity uses the mark on cosmetics and the other uses the mark on trailer hitches, a good argument could be made that the products are not closely related, not marketed in the same way, and not purchased by the same kind of customer.
• How much are the marks alike?
• When spoken out loud, do they sound the same?
• Is one mark a literal translation of the other mark into a foreign language that would be familiar to the public? For example, "Chez Louis" for "Louie's Place."
• Is one mark well known and readily recognized? Think: the golden arches, the little bell in a circle, the Nike swoosh, the CBS eye, the Mercedes hood ornament. And what about Poppin' Fresh, the Green Giant, and Tony the Tiger?
• Is the mark composed of a distinctive phrase or symbol?
• How long have the two marks been in use?
• Has the entity claiming infringement stopped using the mark?
• Is one entity a "free rider?" That is, is the entity using an established name or mark to get an edge in selling the item?
• What did the alleged infringer intend by using the mark?
• Was the use inadvertent?

Has Your Trademark been Infringed Upon? Get Professional Legal Help

The above questions will help you decide whether you may have a legitimate trademark infringement claim, but you really should get a professional opinion. If you believe another party may have infringed upon your company's trademark, contact a trademark law attorney near you.

See FindLaw's Intellectual Property section for more articles and resources.