Thanks to the United States v. Jones Supreme Court decision from January 2012, we now know that law enforcement cannot place a GPS tracking device on someone’s car without a warrant.

But what if you’re merely a passenger in the car—not the owner—and efforts to track the presumed target also track you? According to a new decision (PDF) this week from the Massachusetts Supreme Judicial Court, you’d still have standing to challenge the government’s electronic surveillance of your movements.

The Electronic Frontier Foundation, which filed an amicus brief in the case, applauded the ruling on Friday, noting that “while the decision only applies in Massachusetts, it's important for state courts and legislators to protect their citizens' privacy concerns and build momentum for other state courts and legislatures—as well as federal courts and Congress—to do the same.”

The case involves two men, John Rousseau and Michael Dreslinksi, who were suspected of arson during the summer of 2007 in Massachusetts. The state police acquired a warrant to track Dreslinki’s vehicle for 31 days and proceeded to monitor the vehicle's movements, even when Rousseau was in the car. The men were later arrested, charged, and convicted in separate cases. Both defendants appealed, arguing that the search warrant for GPS tracking was overly broad and therefore violated their rights.

The first appeals court ruled that Dreslinski, as the vehicle’s owner, did have standing to make such an appeal, but Rousseau, as a “mere passenger,” did not. When the appeal went to a higher court, however, a new opinion was reached:

The state high court though, on this second appeal, disagreed with this finding. With respect to the defendants' challenge to the GPS warrant, we conclude that Dreslinski has standing as the owner and operator of the vehicle and that Rousseau, as a passenger in the vehicle, also has standing because he had a reasonable expectation that his movements would not be subjected to extended electronic surveillance by the government through use of GPS monitoring.

The challenges were ultimately moot for the defendants as the court also concluded “that the remaining information was more than sufficient to establish probable cause to issue the GPS warrant,” adding that “none of the fruits flowing from the issuance of the warrant must be suppressed.”