Study each of the following case carefully. Briefly state the principle of law and your decision.

Kenneth Zippo Manufacturing Co. (ZMC) manufactured lighters at its facility in Bradford, Pennsylvania, and sold the lighters internationally. Zippo Dot Com Inc. (ZDC) is a California company that operated a website that allows subscribers to access sexually explicit material. ZMC sued ZDC for trademark infringement in Pennsylvania, but ZDC argued that they should not have to travel to Pennsylvania to defend themselves.