35 U.S.C. § 299 — Joinder of parties

(a) Joinder of Accused Infringers In a patent lawsuit — other than a case involving an act of infringement under section 271(e)(2) — accused infringers can only be joined as co-defendants (or have their cases combined for trial) if: (1) the claim against them arises from the same transaction, occurrence, or series of transactions or occurrences, involving the making, using, importing, offering for sale, or selling of the same accused product or process; and (2) the case will involve questions of fact common to all the defendants or counterclaim defendants. (b) Allegations Insufficient for Joinder Accused infringers cannot be joined together, or have their trials combined, just because they're each separately accused of infringing the same patent — that alone isn't enough. (c) Waiver An accused infringer can choose to waive these joinder limits for themselves.