Today, Fri., May 4, 2012, in In re Misc EMC, Misc. No. 100, the Federal Circuit (Rader, Dyk and Moore) granted mandamus and ordered the  E.D. Tex. district court to reconsider its ruling that allowed joinder of 18 defendants based on a new “sameness test” for joinder (rejecting the district court’s “not dramatically different” test).  The new sameness test appears to limit joinder of multiple defendants in a single case, but the Court noted that cases still may be coordinated in a single court if venue is proper and that multidistrict litigation may be proper for pretrial issues of claim construction and patent invalidity.

This decision provides good guidance on when joinder of independent defendants may be proper.  The court ruled that joinder is not proper based solely on assertion of the same patent claims with common issues of claim construction and invalidity.  The court ruled that “joinder is not appropriate when different products or processes are involved.”  The court explained that, absent linking facts between acts of infringement, joinder may not be proper for “independently developed products using differently sourced parts … even if they are otherwise coincidentally identical.”

The Court gave a non-exhaustive list of factors to consider in applying its sameness test for joinder, including (i) did infringing acts occur in the same time period, (ii) relationship between defendants, (iii) using identically sourced parts, (iv) licensing or technology agreements between defendants and (v) overlap of product/process development and manufacture.  The Court explained that, even if this sameness test is passed, a court may decline joinder if the number of defendants would render case “unwieldy.”

The Court expressly declined to say  whether its sameness test for joinder would apply to the recently enacted misjoinder provisions of the America Invents  Act.