Your Trademark Does Not Need to Be Registered to Be Enforced.
As you are probably aware, a trademark includes any word, name, symbol, or device used in commerce to identify the goods of one manufacturer or seller from goods manufactured or sold by others, and to indicate the source of the goods. In short, a trademark is a brand name such as Coca-Cola(R) for beverages, the Nike swoosh for shoes, and FedEx(R) for package delivery services. What you may not be aware of is that you do not have to own a federally registered trademark to enforce your rights in a trademark (i.e., stop someone else from infringing or knocking off your mark with a similar or identical mark). Trademarks can be federally registered and the federal registrations are well worth the time and effort to acquire. But trademarks also exist at what is known as common law. In short, if you are using a trademark to identify your goods or services, even if you have never registered the same, you have acquired rights in that mark back to the date that you first used the mark.
You Need to Have Used Your Trademark First.
Probably the most important issue in trademark enforcement is to figure out who used their respective trademark first. The general rule is that whoever used their mark first has what is known as Priority of Use. The person who used it second has Inferior Use. Accordingly, the party with the Priority of Use can enforce their mark against the party with Inferior Use (e.g., make them stop using the infringing mark). With every rule there are exceptions. But this general rule is a good guiding point if you are thinking about enforcing your mark.
The Trademarks Need to Be Similar.
When you look at your mark and the other mark do you feel that they are very similar? The general rule is that if the marks are similar in appearance, spelling, phonetic pronunciation, or simply present a similar overall commercial impression enforcement may be had. So unless the marks are identical, this is generally a subjective sliding scale.
The Goods and/or Services Need to be Similar or Related.
Also, to enforce your mark against another the goods and/or services need to generally be similar enough that the average consumer encountering the respective trademarks would think that they originate from the same source. To put it another way, few would argue that if we started seeing frozen hamburger patties in our grocery store with the brand "McDonalds" on them we would think those nice people from Illinois are now making frozen food as well. Although they have never delved into the frozen food market, there is a strong enough association between the two that the assumption would be logical. So like the subjective rule of reason we talked about with the similarity of the marks, this is also a subjective exercise.
Is Enforcement a Good Business Decision?
This is one that attorneys don't often speak about with their clients but we like to bring up -- Does enforcement of the mark make good business sense? Yes you are angry someone is knocking off your mark. Sure it is nearly identical to yours. But does a single mom and pop store opening in California affect your bottom line in the New York / New Jersey area where you distribute your products? We look at it like this. At the end of the day when you are deciding to enforce your mark you need to make a BUSINESS DECISION as to whether enforcement makes sense. For every situation there is a different answer. It's a factual analysis the business owner must make.