A stack of internal e-mail messages from Google, which a Massachusetts state court made public last week, provide a glimpse into the competitive tactics and decision-making inside a business that is crucial to the company’s growth — its Android software for smartphones.

Android is Google’s gateway technology to a lucrative new arena for mobile advertising. Google provides the Android operating system free to handset makers, and allows them to tailor the open-source software somewhat, yet limits their freedom to tinker.

Android phones must adhere to a “compatibility” standard determined by Google. In an e-mail on Aug. 6, 2010, Dan Morrill, a manager in the Android group, noted in passing that it was obvious to the phone makers that “we are using compatibility as a club to make them do things we want.”

Whether that club is an anticompetitive weapon is an issue in the court case.

Yet industry analysts see another motivation as well. In the smartphone market, they say, Google faces the challenge of being the creator of a popular operating system that must work smoothly with hardware and software made by other companies. In broad strokes, Google’s predicament echoes the past.