At this point, why wouldn't Democrats pack the court?

He was asked by moderator Chris Wallace whether the Republican-controlled Senate's unseemly rush to replace liberal judge Ruth Bader Ginsburg with President Trump's conservative nominee Amy Coney Barrett just before the election would prompt him to neutralise or reverse the balance of the court by increasing its size.

After much deflection and interjection by Trump asking "Are you going to 'pack' the court?", Biden said: "I'm not going to answer the question."

You could hardly get a clearer indication that increasing the size of the court is on the Democrats' agenda if they win the presidency and the Senate. And good thing, too.

Given that the Republicans blocked President Obama's nomination in an election year in 2016, the Democrats might well argue that one dirty trick deserves another - or that the Republicans' packing of the court deserves to be unpacked.

A lot is at stake here. In most countries, legislatures determine most critical questions. The laws can be changed, repealed or amended fairly easily. But in the US, a huge number of questions are determined by judges, and at their apex is the Supreme Court.

Because of the Bill of Rights and other amendments to the US constitution, the remit of the court runs wide. It has ruled that there are things beyond the federal and state legislatures. There are things the legislatures cannot do. And these often-fractious things directly affect the lives of Americans.

The court has told the legislatures that their power to prohibit abortions, restrict marriage to couples of opposite sex, restrict gun ownership and possession, or force people to have health insurance is limited. Capital punishment was on that list until 1976.

Broadly, the left applauds the first two and the right applauds the last two.

Nearly all the decisions on these matters have been decided by 5-4 majorities, so it has been crucial for each side to "pack" the court with judges they think will change the rulings on these matters whenever they get the chance - even if it means overlooking jurisprudential giants for ideological lightweights.

With lifetime tenure, it takes a long time for the composition of the court to be altered in such a way that the court might change its earlier rulings. So a lot is at stake when a position comes up.

From a Democratic perspective, having struggled away in the legislature to get universal health insurance, you don't want it torn down by a court packed with Republican appointees.

From a Republican point of view, having got a draconian anti-abortion law through a legislature, it would be nice to have it enforced rather than left unenforceable by the Supreme Court's 1973 decision in Roe v Wade.

And what is the point of passing laws to control guns, if the Supreme Court is going to strike them down?

With all that at stake, "packing" the court is a sensible option. Small wonder Biden did not want to rule out that possibility.

But it is an uncertain business. Often judges appointed by Republicans have turned liberal or centrist, and Democrats' appointments have turned conservative. The judges are not bound by party rules. But they are at least notionally bound by the doctrine of precedent, which means that earlier decisions should be followed. It is one of the reasons Roe v Wade has held up for nearly half a century.

The Republicans' religiously inspired desire to see Roe v Wade overturned has made them seek out potential nominees who have expressed a willingness not to follow precedent in constitutional cases.

Barrett is one such judge. But this is a double-edged sword which could backfire, if you will pardon the mixed metaphor and the upcoming pun. What if a precedent-unshackled Barrett decides she is not bound by the dubious jurisprudence that underpins the Supreme Court's inclination to allow people to arm themselves to the teeth?

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If an administration is not willing to wait for enough judges to die so they can pack it with their own kind, the other option is to increase the court's size.

As in Australia, the US constitution does not stipulate the size of the court; the legislature does. Congress has not changed the size of the court since it was set at nine in 1869.

In 1937, after the court struck down much of the progressive New Deal legislation of the administration of Franklin Roosevelt, Roosevelt moved to increase the size of the court to 15. It did not get through the Senate, but perhaps the thought of it caused the judges to allow more of his legislation through, because that was the upshot.

Some have suggested that the justices should have term limits of 18 years, so at least one would be appointed every two years. But that would require a constitutional change and be unlikely.

Republicans thwart the democratic will by every trick they can - the filibuster in the Senate, packing the court by refusing the Democrats a nomination because it was an election year in 2016 but pushing on with their own in 2020, rigging electoral boundaries in Republican-held states and so on.

That being the case, the Democrats should do the same thing to protect the democratic will. After all, the great majority of Americans support a woman's right to choose an abortion, especially early in the term, and large majorities want gun control and universal health insurance.

If the Democrats win the presidency and both houses of Congress, why should they put up with five or six diehard justices blocking their policy wins at will when they could increase the size of the court to 13 or 15 and appoint some judges who would see things differently?