In May 2000, BLP filed suit in the US District Court of Columbia, saying that withdrawal of the application after the company had paid the fee was contrary to law. In 2002, the District Court concluded that the USPTO was acting inside the limits of its authority in withdrawing a patent over whose validity it had doubts, and later that year, the United States Court of Appeals for the Federal Circuit ratified this decision. Applications were rejected by the UK patent office for similar reasons. The European Patent Office (EPO) rejected a similar BLP patent application due to lack of clarity on how the process worked. Reexamination of this European patent is pending.