Adam sued Saenger in Texas for
something or other.
Adam established that the
Texas court had jurisdiction to hear the case.
Saenger countersued. Adam
appealed the counterclaim.
Adam argued that he did not
consent to the counterclaim, therefore the Texas court did not have
jurisdiction to hear it.
The US Supreme Court found for
Saenger and allowed the counterclaim to proceed.
The US Supreme Court found
that if you consent to one part of the litigation, you've consented to
all of the litigation.
Therefore, if you sue
someone, and it's determined that you've got the jurisdiction to sue
them, then they logically have the jurisdiction to sue you back.