A conflict could arise in the future, if, for example, Aearo and 3M disagreed about the terms of a future settlement, Graham said.
If that happened, Kirkland could face disqualification, loss of fees, or even potentially the dismissal of Aearo's bankruptcy case, according to the judge.
Kirkland has defended 3M in the MDL, and it represents Aearo in the bankruptcy case that was meant to spur a settlement of the earplug lawsuits.
The plaintiffs and the U.S. Department of Justice's bankruptcy watchdog sought to disqualify Kirkland from representing Aearo in the bankruptcy, saying it could not faithfully serve both Aearo and 3M.
The case is Aearo Technologies LLC, U.S. Bankruptcy Court for the Southern District of Indiana, No.