If a patent owner believes another person or entity is infringing on their patent, the patent owner can enforce their patent rights by bringing a patent infringement lawsuit. Because patent law is a matter of federal law (as opposed to state law) patent infringement lawsuits must be filed in federal court.
Patent litigation is notoriously expensive for plaintiffs and defendants. For defendants, these high costs mean they may prefer to settle rather than fight patent litigation suits they view as being without merit. This possibility of obtaining a settlement—without the defendant challenging the merits of the case—in turn increases the expected value of frivolous patent litigation, and creates additional incentives for these lawsuits to be filed.
On the other hand, well-financed defendants can outlast entrepreneurs with fewer resources—which may force plaintiffs with valid patent infringement cases to accept settlements that are favorable to the defendants.
Patents and patent litigation are complex areas of law and a potential plaintiff or defendant should consult with an experienced patent lawyer at the first prospect of litigation.