A startup fertilizer company can proceed with claims that a Koch brothers-owned competitor is trying to drive it out of business through litigation based on a questionable patent, a North Carolina federal judge has ruled.

Eco Agro Resources made its allegations as counterclaims in a patent infringement suit brought against it last year by Koch Agronomic Services. That suit claimed Eco Agro's stabilized nitrogen fertilizer N-Yield, which competes with Koch's market-leading Agrotain, violated patents held by Koch.