What is Section 15 Affidavit?

A Section 15 affidavit is a declaration filed with the United States Patent and Trademark Office under Section 15 of the Lanham Act (15 U.S.C. Section 1065) that claims incontestable status for a registered trademark. To qualify, the mark must have been in continuous use in commerce for five consecutive years after registration, with no final adverse decision in any proceeding challenging the owner's right to use the mark. Once accepted, the registration becomes "incontestable," meaning it is immune from challenge on most grounds that could otherwise be raised to cancel it.

The Section 15 filing is optional — there is no requirement to claim incontestability, and no penalty for not doing so. However, filing it provides significant legal advantages. It is typically filed at the same time as the Section 8 affidavit (between the fifth and sixth year after registration) to streamline the process, though it can be filed at any time after the five-year continuous use threshold is met.

Incontestable status does not make a trademark absolutely immune from all challenges. A registration can still be cancelled on limited grounds even after achieving incontestability — including that the mark has become generic, that it was obtained by fraud, that it has been abandoned, or that the mark is being used to misrepresent the source of goods. However, the most common grounds for cancellation — such as mere descriptiveness or likelihood of confusion with a prior mark — are no longer available against an incontestable registration.

Why It Matters

Incontestability is one of the most powerful defensive tools in U.S. trademark law. A trademark with incontestable status has survived five years of continuous use and scrutiny, and the owner's exclusive rights are treated as conclusive rather than merely prima facie. This significantly strengthens the owner's position in infringement litigation, as the defendant cannot attack the validity of the mark on descriptiveness or other grounds that would otherwise be available.

The practical impact is substantial. In enforcement actions, an incontestable mark puts the burden on the infringer to prove one of the narrow exceptions rather than allowing a broad attack on the mark's validity. Licensing negotiations also benefit, as licensees have greater confidence that the licensed mark cannot be easily challenged.

How Signa Helps

Signa's API provides access to the maintenance filing history of U.S. trademark registrations, including whether a Section 15 declaration has been filed and accepted. This data is valuable for both offensive and defensive trademark strategies. During clearance, knowing that a potentially conflicting mark has achieved incontestable status affects the risk assessment — challenging an incontestable mark is significantly harder than challenging a contestable one.

Signa's monitoring tools also track the five-year milestone for a user's own registrations, prompting timely filing of Section 15 affidavits to lock in incontestable status before any adverse proceedings arise.

Real-World Example

A specialty coffee chain registered "Roastcraft" with the USPTO six years ago for coffee shop services in Class 43. The brand has been in continuous use since registration with no legal challenges. On the advice of their attorney, the chain files a Section 15 affidavit alongside their Section 8 declaration, claiming incontestable status. Two years later, a competitor opens a coffee shop called "RoastKraft" and, when challenged, argues that "Roastcraft" is merely descriptive of the craft coffee roasting process and should never have been registered. Because the registration is incontestable, the court rejects this defense. The competitor cannot challenge the mark on descriptiveness grounds and is ultimately found to have infringed, resulting in an injunction and damages award. Without the Section 15 filing, the descriptiveness argument might have succeeded in weakening or cancelling the registration.