Myriad Genetics is once again embroiled in litigation over its BRCA-related patents. But this time Myriad is the defendant. Counsyl, Inc., a San Francisco-based company that focuses on genetic carrier testing, sued Myriad in U.S. District Court for the Northern District of California on September 20, 2013. As we noted in an earlier post, Myriad — as a plaintiff — has recently sued two small companies, Ambry and Gene By Gene, that have entered the BRCA testing market in response to the Supreme Court decision invalidating Myriad’s gDNA patent. Myriad presumably filed those suits — against vulnerable defendants — to send a message that it would maintain its testing monopoly by enforcing patent claims that had survived the earlier litigation. But it took the risk that the defendants might succeed in invalidating those surviving claims. Now, with the Counsyl suit, the BRCA controversy has entered a new stage, with a prospective competitor launching a preemptive strike against Myriad and its patents.