A federal agency ruled on Monday that a set of important features commonly found in smartphones are protected by an Apple patent, a decision that could force changes in how Google’s Android phones function.

The ruling, by the United States International Trade Commission, is one of the most significant so far in a growing array of closely watched patent battles being waged around the globe by nearly all of the major players in the mobile industry. These fights reflect the heated competition among the companies, especially as Android phones gain market share.

At the heart of the disputes are the kind of small but convenient features that would cause many people to complain if they were not in their smartphones. For example, the case decided Monday involves the technology that lets you tap your finger once on the touch screen to call a phone number that is written inside an e-mail or text message. It also involves the technology that allows you to schedule a calendar appointment, again with a single tap of the finger, for a date mentioned in an e-mail.

HTC, the defendant in the case and a Taiwan-based mobile phone maker using the Android system, said in a statement after the ruling that it would adapt its features to comply with the court’s decision. The company called them “small” parts of the user’s experience.