Roberts’ action recalled his dramatic switch in the 2012 case that saved President Barack Obama’s Affordable Care Act. Once again, the chief, an appointee of President George W. Bush and a reliable conservative, had sided with the liberals as a dispute of immense national significance went down to the wire.

More broadly, his moves in the census dispute demonstrate that as he begins his 15th year as chief justice, Roberts has become less predictable. He is wearing the heavy mantle of a vote at the middle of a divided bench in this new chapter of his tenure, with the 2018 retirement of centrist-conservative Justice Anthony Kennedy and a solid 5-4 conservative majority.

For the most part, Roberts’ opinion in the census case laid out why Commerce Secretary Wilbur Ross had significant latitude to add a new question. He was joined by his four conservative brethren on that point. But then the chief justice swerved, and joined by the four liberal justices, said Ross’ justification for the citizenship question, tied to enforcing the Voting Rights Act, was contrived.