Your Google search history can be used against you in court. Does that violate the Constitution?

Criminal investigators hoping to develop suspects in difficult cases have been asking Google to reveal who searched for specific information online, seeking “reverse keyword” warrants that critics warn threaten the privacy of innocent people.

Unlike traditional search warrants that target a known suspect or location, keyword warrants work backward by identifying internet addresses where searches were made in a certain window of time for particular terms, such as a street address where a crime occurred or a phrase like “pipe bomb.”

Police have used the method to investigate a series of bombings in Texas, the assassination of a Brazilian politician and a fatal arson in Colorado.

It’s not a wild guess by investigators to conclude that people are using Google searches in all manner of crimes, as the company’s search engine has become the main gateway to the internet and users’ daily lives increasingly leave online traces. The potential value to investigators of the data Google collect...