Leviton Manufacturing Co., Little Neck, N.Y., recently announced it has filed a second lawsuit against Universal Security Instruments, Inc. (USI), an importer of ground fault circuit interrupters (GFCIs). The suit was filed in the U.S. District Court of Maryland and states that USI is willfully infringing patents covering the lockout feature used in Leviton’s SmartLock GFCI, a design feature that complies with the January 2003 UL 943 Requirements.

The lawsuit is the second Leviton has filed against USI. It claims that USI’s 2003 UL-compliant GFCIs infringe on at least six current patents Leviton holds on its SmartLock GFCI.

In 2001 Leviton filed an earlier suit against USI seeking a permanent injunction and recovery of treble damages and legal fees for USI’s infringing on an older Leviton GFCI patent.