In most cases, the accused infringer will also assert one or more counterclaims. Most of the time these counterclaims will be a request for a declaratory judgment of non-infringement and/or invalidity of the patent at issue.

In extreme cases, the accused infringer may assert an antitrust counterclaim. These antitrust counterclaims can take two forms:

1. When a party files a sham lawsuit
2. When the patentee commits intentional fraud upon the USPTO

The standard for a successful antitrust counterclaim is extremely high. Consequently, successful counterclaims for an antitrust violation are quite rare.

The accused infringer may also assert defenses, such as unfair competition or intentional interference with contractual relations. However, it should be noted that the patentees are provided a certain degree of privilege to make infringement claims, so that the patentees’ conduct must be very egregious to justify such counterclaims.