Donald Trump's nominee for Supreme Court Justice has been sworn in despite vehement Democrat opposition, which forced Republicans to use the "nuclear option" and change the rules so his nomination could pass.
"To whom much is given, much is expected," Neil Gorsuch said as he became the 113th person to take up the lifetime appointment in the US's highest court.
Mr Trump was in "no doubt" about his pick, telling him that he would "go down as one of the truly great justices" in history.
Mr Gorsuch took the constitutional oath in a private ceremony, administered by Chief Justice John Roberts in the Supreme Court’s Justice’s Conference Room.
He was accompanied by his wife Louise, who held the Bible, and his two daughters, Emma and Belinda as well as all eight of the justices, who will now become his colleagues.
Maureen Scalia and Eugene Scalia, the widow and son of the justice Mr Gorsuch is replacing, Antonin Scalia, were also in attendance.
In a second ceremony at the White House, Justice Anthony M Kennedy, for whom the 49-year-old Mr Gorsuch once served as a clerk, led him through a second oath that justices take, to impartially interpret the laws “and do equal right to the poor and to the rich”.
Mr Gorsuch's nomination followed a bitter battle in the Senate.
Democrats were furious that Republicans had blocked Barack Obama's nominee Merrick Garland to replace Justice Scalia. Senate majority leader Mitch McConnell refused to consider his nomination in the last congressional session, citing the election-year politics.
After Mr Gorsuch's nomination last week, Democrats blocked his nomination with a procedural filibuster – the first time in history this has happened.
Republicans responded with the "nuclear option", a dramatic and historic change in the Senate rules allowing Mr Gorsuch and all future Supreme Court nominees to pass through the Senate with a simple 51-vote majority instead of the previous 60-vote threshold.
The two-thirds majority was not expressly outlined in the US Constitution, but was a general Senate practice.