Here's a less dumbed-down article from a bit earlier in the process: https://www.law.com/dailyreportonline/sites/dailyreportonlin...
A 2012 law created an administrative review system for challenging patents, meant to reduce the expense of challenging patents by keeping the process out of court. That law was challenged as being an illegal taking happening outside a court of law. The Supreme Court disagreed, considering it just a corrective action of the patent office's discretionary granting abilities. More or less.