The Supreme Court’s blunt and unequivocal decision Wednesday giving Americans strong protection against arrest-related searches of their cell phones could also give a boost to lawsuits challenging the National Security Agency’s vast collection of phone call data.

Chief Justice John Roberts’s 28-page paean to digital privacy was like music to the ears of critics of the NSA’s metadata program, which sweeps up details on billions of calls and searches them for possible links to terrorist plots.