A trademark, which can be a name, symbol, catchphrase or logo, distinguishes a company's products from the competition. A company that wants to protect its trademark can file to register it with the federal government. Registration strengthens a company's legal claim to the mark. If your company wants to dispute a competitor's claim, you can challenge the registration.
Watch the Calendar
Even if you have an airtight case to contest the trademark, you need to act on it promptly. When the US Patent and Trademark Office considers registering a mark, it announces this in the weekly online "Official Gazette." Once the announcement comes out, you have 30 days to file your objections in writing. If you need more time, you can request an extension. International law says you get a maximum 180 days to file a challenge to an international trademark, with no extensions beyond that.
Find the Flaws
To contest the filing and win you have to show your competitor's trademark isn't suitable for registering. If it's so close to your own mark that it would confuse buyers, for instance, that would disqualify it. You can also challenge the mark on the grounds that it's too generic. It's unlikely a restaurant, for example, could trademark "good food" or "fine dining," because those words aren't a distinctive slogan. If the competitor hasn't used its trademark in years, you may be able to claim it has abandoned it.
Petition to Cancel
The most cost-effective way to contest the filing is with a petition to cancel. This is an administrative petition filed with the trademark office, so it saves you the costs of going to court. You state the reasons you're contesting the mark, and if the government agrees, it cancels registration. If you're challenging the filing to protect your own trademark, the petition method has a risk: your competitor can file a counter-petition to invalidate your trademark instead.
Constructive Use
Blocking the trademark filing may not prevent your competitor from using the mark. The "constructive use" doctrine says that if the company has used the mark for years in, say, California, it can keep on using it even if you use the same mark in other states. Constructive use works both ways, though. If your competitor successfully register a trademark you're already using in your sales region, you may be able to keep right on using it.

Even if you have an airtight case to contest the trademark, you need to act on it promptly. When the US Patent and Trademark Office considers registering a mark, it announces this in the weekly online "Official Gazette." Once the announcement comes out, you have 30 days to file your objections in writing. If you need more time, you can request an extension. International law says you get a maximum 180 days to file a challenge to an international trademark, with no extensions beyond that.
Find the Flaws
To contest the filing and win you have to show your competitor's trademark isn't suitable for registering. If it's so close to your own mark that it would confuse buyers, for instance, that would disqualify it. You can also challenge the mark on the grounds that it's too generic. It's unlikely a restaurant, for example, could trademark "good food" or "fine dining," because those words aren't a distinctive slogan. If the competitor hasn't used its trademark in years, you may be able to claim it has abandoned it.
Petition to Cancel
The most cost-effective way to contest the filing is with a petition to cancel. This is an administrative petition filed with the trademark office, so it saves you the costs of going to court. You state the reasons you're contesting the mark, and if the government agrees, it cancels registration. If you're challenging the filing to protect your own trademark, the petition method has a risk: your competitor can file a counter-petition to invalidate your trademark instead.
Constructive Use
Blocking the trademark filing may not prevent your competitor from using the mark. The "constructive use" doctrine says that if the company has used the mark for years in, say, California, it can keep on using it even if you use the same mark in other states. Constructive use works both ways, though. If your competitor successfully register a trademark you're already using in your sales region, you may be able to keep right on using it.