Neil Gorsuch
US President Donald Trump and Neil Gorsuch - Trump nominated Gorsuch to be an associate justice of the US Supreme Court Kevin Lamarque/Reuters

It is little surprise that the battle to fill vacant seats on the US Supreme Court is such a bitter one: American presidents are elected for a maximum of eight years but appoint judges that serve for life.

Neil Gorsuch, Donald Trump's candidate to replace Antonin Scalia, is 49 and if he is confirmed by the Senate he would be the youngest supreme court judge to be appointed since 1977. Given that three of the judges on the bench are now in their 80s, Gorsuch could feasibly serve for the next 40 years.

Scalia was a conservative – a so-called 'originalist' that believed that the US Constitution should be stuck to rigidly despite being written some 200 years ago – and so is Gorsuch, so if he is appointed judges that are considered 'liberal' in outlook would once again be outnumbered on the bench.

Critics are concerned that Gorsuch's appointment will enable conservative judges to roll back reforms on gay rights, abortion and immigration. Republicans had made the vacant supreme court seat a key electoral issue, urging voters to give the right to fill it to a conservative rather than a Democrat.

During the past year the court was divided 4-4 on contentious issues including unions and immigration but Democrats fear that issues such as abortion and gay rights could also be in jeopardy under a conservative-dominated supreme court.

But while there has been a backlash about Gorsuch's nomination, the Colorado judge was one of the more moderate of the potential candidates that had been linked to Trump ahead of his announcement on Tuesday night. Gorsuch is well regarded – even amongst Democrats.

Trump was also considering William Pryor Jnr, the former Alabama attorney general who has backed controversial policies such as the practice of chaining prison inmates to hitching posts in the hot sun if they refuse to work. He has called Roe v Wade, the law that made abortion legal, 'an abomination'.

Like many supreme court judges, it is not black and white. Critics on the right brand Pryor a liberal for various ruling where he has defended the rights of transgender workers and forced a former chief justice to remove a two-ton monument to the Ten Commandments at the Alabama state judiciary.

Many Democrats are bitter about the appointment of Gorsuch not because of his politics but because the Republicans blocked Barack Obama's efforts in 2015 to have Merrick Garland appointed to Scalia's seat. Republicans argued it was wrong for an 'outgoing president' to make a life-time appointment.

A Reuters poll found in July 2015 that a majority of Americans would support terms of 10-years for judges.

But Republicans could well point out that – in terms of numbers – Obama had a pretty good run. Sonia Sotomayor, 64, and Elena Kagan, 58, were both appointed to the Supreme Court by the last president. George W Bush appointed two justices, and George HW Bush one.

Bill Clinton also has two appointees, Ruth Bader Ginsburg, 83, and Stephen Breyer, 80, and the final judge is a Ronald Reagan era-appointment, Anthony Kennedy, 81. Once Trump gets Gorsuch on the bench, it is to these three Clinton and Reagan-era judges which attention will turn.

Ginsburg and Breyer are both considered progressive and Kennedy can go either way, occasionally voting with his liberal counterparts against conservatives. All three are in their 80s, and should any pass away during Trump's presidency, he will be able to tip the balance towards the right.

Should other seats become available, Donald Trump's nominations may not be as conventional as Gorsuch, who is a traditional conservative and an obvious choice to please the Republican base, particularly those who may still not have come over to the US president's bombastic leadership.

Over the years there have been calls for term limits to be imposed on the Supreme Court, and a Reuters poll found in July 2015 that a majority of Americans would support terms of 10-years for judges. However the move would be contentious – involving a change to the US Constitution.

And with the Republicans in control of both the House of Representatives and the Senate, there is little incentive for them to do so. Democrats will almost certainly lose the battle over Gorsuch's nomination – but the war over the future of the Supreme Court may only just be beginning.