Still in hot water with his former boss, Facebook CEO Mark Zuckerberg is facing another lawsuit - this time, for direct patent violation.

Filed last month in Pennsylvania, the lawsuit claims Facebook violates an existing patent covering a "system for creating a community for users with common interests to interact in." The patent is owned by Cross Atlantic Capital Partners, reports TechCrunch.

Facebook, which organizes networks around universities, work groups and other interests, makes for a savory target.

But having opened its doors to any and all users, the question remains over whether the patent infringement accusation will carry any weight.