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IN THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF MARYLAND LEVITON MANUFACTURING COMPANY, INC., Plaintiff : : : : v. : : UNIVERSAL SECURITY : INSTRUMENTS, INC., et al., : Defendants : : : : : SHANGHAI MEIHAO ELECTRIC, INC., : Plaintiff/Counter-Defendant : : v. : : LEVITON MANUFACTURING : COMPANY, INC., : Defendant/Counter-Plaintiff : ...o0o...

Civil No. AMD 03-1701

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Civil No. AMD 03-2137

MEMORANDUM OPINION SETTING FORTH CLAIMS CONSTRUCTION Leviton Manufacturing Company, Inc. ("Leviton") filed suit against Universal Security Instruments, Inc., and USI Electric, Inc. (collectively "USI"), on June 10, 2003 for, inter alia, infringement of six Leviton patents which cover improvements in ground fault circuit interrupter ("GFCI") technology. USI is a customer of Shanghai Meihao Electric, Inc. ("Meihao") and purchases and resells Meihao's GFCIs. On July 23, 2003, Meihao filed a declaratory judgment action against Leviton, alleging, inter alia, that Meihao's products at issue, GFCIs equipped with reverse wiring protection, do not infringe any of the six patents and that the patents are invalid and/or unenforceable. Leviton filed a counterclaim against Meihao for infringement of the patents. In July 2004, I consolidated the two cases for purposes of discovery, the Markman hearing on claim construction, and other pre-trial proceedings. The Markman hearing was held on March 3, 2005.

This opinion sets forth my construction of the claims at issue. I. A GFCI protects a consumer from electric shock and electrocution when an electrical device, which is connected to an electrical power source, experiences a ground fault. A ground fault occurs when a separate current path is created in addition to the current flowing from the electrical power source through the electrical device and back to the power source. This may happen, for example, due to wear and tear of the electrical device or when the electrical device becomes wet. When a GFCI detects a ground fault, the GFCI causes the electrical circuit to "trip", i.e., to open, and the flow of current is stopped. After the circuit is interrupted, the GFCI can be reset so that electrical current is again allowed to flow through the electrical circuit. Leviton is the owner of six patents, U.S. Patent Nos. 6,040,967 (the "`967 patent"), 6,381,112 (the "`112 patent"), 6,282,070 (the "`070 patent"), 6,246,558 (the "`558 patent"), 6,288,882 (the "`882 patent"), and 6,437,953 (the "`953 patent") (collectively the "Leviton Patents"), which cover improvements in GFCI technology. The patents are interrelated. The parent patent is the `967 patent. The `112 patent is a continuation1 of the `967 patent, the `070 patent is a continuation-in-part2 of the `967 patent, the `882 patent is a continuation-in-part of the `070 patent,

A continuation application is an application that is filed during the pendency of an application previously filed by the same inventor, that discloses and claims only subject matter disclosed and claimed in the original or parent application, and that is entitled to the parent's filing date. See 35 U.S.C.

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Maryland Law