The brouhaha began with the typical patent battle shortly before a drug is weaned off patent protection, and generic makers jockey for market position by filing an ANDA with the FDA for permission to make their knock-off version. The FTC began its fitful investigation after the parties patched up the spat with an agreement, where the generic makers could market their own versions in return for kickbacks. That sort of marketplace back-scratching aggrieves the FTC, which has challenged numerous reverse payment agreements over the past few years, with scant success, as the courts view patents as an antitrust exception: "A patent by its very nature is anticompetitive."