n.a suit brought against someone who has sued you

Tunable Laser Countersuit Filed
Suit and countersuit for Alaska and Exxon
Folkman countersuit attacks "fraudulent"Abbott.
Contract leads to suit, countersuit
Blue Buffalo Files Countersuit Against Nestle Purina
FT: StanChart seeks advice over countersuit
It Is Time to End the Lawyer's Immunity from Countersuit
Messy Breakup: Tiffany Hits Swatch with $590M Countersuit
Current TV Fires Back Against Keith Olbermann With A Countersuit
SLAPP/SLAPPback: The Misuse of Libel Law for Political Purposes and a Countersuit Response