WASHINGTON – When last we saw the chief justice of the United States on the bench, John Roberts was joining with the Supreme Court’s liberals in an unlikely lineup that upheld President Barack Obama’s health care overhaul.

Progressives applauded Roberts’ statesmanship. Conservatives uttered cries of betrayal.

Now, the Supreme Court is embarking on a new term beginning Monday that could be as consequential as the last one, with the prospect for major rulings about affirmative action, gay marriage and voting rights.