If you want a sure-fire way to separate a roomful of people into two factions, progressive and conservative, just mention the words abortion rights. In the last couple of weeks this has again become a red-hot topic on both sides of the Atlantic, in Washington and also in Warsaw. But this time there is a twist.

Poland has some of the strictest abortion laws in Europe. Under them, abortion is prohibited completely except in cases of rape, incest, direct threats to the mother’s health and serious foetal abnormality. In practice the vast majority of legal terminations – over 95% – have taken place under the last of these rubrics.

No longer, however: the matter has now been upset by a court decision that the law is – wait for it – not strict enough. On Thursday last week the supreme constitutional court ruled that allowing termination on the basis of abnormality was itself unconstitutional, as it infringed the constitutional rights to human dignity and non-discrimination. The result of the ruling was, as one might have expected, immediate and vociferous. Widespread demonstrations by feminist and pro-choice groups followed. Amnesty, the Council of Europe and Human Rights Watch immediately laid into the decision as an unjustified attack on women’s rights; the latter body went as far as to demand intervention by the EU Commission to do something about it on the basis that it was an infringement of EU values.

Meanwhile something close to a mirror image of events in Poland is being played out in Washington. The scene is the confirmation hearings for Trump appointee Judge Amy Coney Barrett, Trump’s candidate for appointment to the Supreme Court to replace Ruth Bader Ginsburg, who died earlier this year. The looming background to these hearings, indeed for some the only background that matters, is the issue of Roe v Wade.

Summed up, this was an enormously controversial 1973 decision of the US Supreme Court saying by a 7-2 majority that, although the Constitution neither mentions abortion nor contemplated it in 1787, there could be extrapolated from it an implied right to it. Slightly simplified, there is an almost unregulated right to termination during the first trimester, and a rather more nuanced right during the second. Being constitutional, this is a right that state law, which would otherwise regulate the matter, cannot gainsay.

The Supreme Court can however always change its mind and overrule Roe v Wade. Furthermore, changes in its personnel in the last fifty years mean this is a tangible possibility. Donald Trump makes no secret that this is something he would like to see happen.

Hence the importance of Amy Coney Barrett. Professionally, she has dodged questions about how she would vote on the issue. She is of course right to do so: judges are there to judge, not to prejudge. But as a matter of practicality there is little secret about her personal unhappiness with the decision. She is not only an instinctive conservative but a very devout Catholic, and also openly bears the Trump seal of approval. Not surprisingly, the prospect of her confirmation has sundered the country between conservatives and progressives in the same way as events in Poland, with concerted demonstrations by pro-lifers and pro-choicers across the US.

What should we make of this? The answer is not what you might think. In Poland the radicals are right, though (as we will see) their reasoning is not, and you should support them. In the US they are wrong, and Judge Barrett deserves your support.

The issue is how we ought to decide the question of the extent of abortion rights. Should they be constitutionalised, or left up to the rough and tumble of democratic politics?

The reason isn’t anything to do with the rights and wrongs of abortion. The Polish protestors remain entitled to your backing even if you are an ultramontane Catholic; and you ought to support Judge Barrett even if you are an adamantly pro-choice radical. The issue is how we ought to decide the question of the extent of abortion rights. Should they be constitutionalised, or left up to the rough and tumble of democratic politics? The answer is the latter. The objection to the restriction of abortion rights by the Polish judges last week is that it defied democracy; the reason wholeheartedly to support the reversal of Roe v Wade is that it will restore it.

The point is that personal constitutional rights (or claims based on some concept of human rights, which are much the same thing) need to be recognised as something wholly exceptional. Allowing them is justified if, and only if, they reflect one of two things. The first is claims against the state so obvious as to be beyond controversy; the right not to suffer state practices which no decent state should be able to engage in and still call itself civilised. Examples are state-sponsored murder, deliberate and blatant torture, arbitrary arrest for no reason, wholesale confiscation of property. The other is things without which a reasonably democratic state is impossible: a reasonably wide franchise, equal voting rights, uncorrupt elections, and free speech.

What this specifically does not include is matters of social policy where disagreement is possible between reasonable people. In such a case there is every reason why the decision should be entrusted to the democratic political process; indeed this is exactly what that process is for. You can thus have diversity between states where people think differently; the possibility of change where public mores change; and the entirely healthy need for those advocating social measures to persuade others that they are a good idea before they can be imposed. Moreover, this remains so however important the social policy is. Despite the tendency of the human rights establishment, including at least some of our own Supreme Court judges, to think that the more significant a matter is the greater the reason to entrust it to enlightened liberal experts and limit the power of voters in that respect, actually the opposite is true: if we believe in the right of a people to direct its own destiny, then the more important a given question, the more vital it is to subject it to democratic decision and not entrust it to a particular elite group to do as it thinks fit.

Abortion rights are pretty clearly something falling into this category. True, they concern absolutely vital issues of life, death and female autonomy. But they are not a matter beyond argument either way. This is shown by the complexity and ultimate inconclusivity of disputes about the absolute value of life, whether life begins at conception, and how far a child in utero can be regarded as a separate being or merely a growth subject to the will of the owner of the uterus.

If this is right, then the answer is clear. In Poland the question should simply be whether the law passed by the Polish parliament allows abortion for foetal anormality; if it does, there is no reason to allow it to be changed by judicial fiat. Indeed this is doubly true in the murky Polish political context, where it seems that the ruling party in Parliament would have been happy to change the law, but declined to do it directly because it did not wish to stir up a hornets’ nest. Instead it chose the coward’s course of throwing the matter to the constitutional court, most of whose judges the ruling party had actually appointed but whose decisions it could sanctimoniously distance itself from. This is not a practice to be encouraged.

Hence the protestors are right. Not that this is necessarily for the right reasons. Most would be very happy with non-political solutions: for example, they would love it if the constitution actually protected abortion rights against democratic limitations, or if the Polish government was told by the European Court of Human Rights to liberalise its laws and felt itself constrained to obey. Human Rights Watch’s call for EU intervention is if anything even more unpleasantly authoritarian and undemocratic. Nevertheless, the protesters are correct in calling out the decision, and deserve the backing of anyone who takes democracy seriously.

Reversing Roe v Wade would not be an authoritarian move; it would be a fundamentally liberating one, throwing the matter back to the electors in the 50 States (roughly half of whom, remember, are female)

In the US, by contrast, it is rather different. Reversing Roe v Wade would not be an authoritarian move; it would be a fundamentally liberating one, throwing the matter back to the electors in the 50 States (roughly half of whom, remember, are female). Nor, for that matter, would it amount to any kind of ban on abortion: that would remain up for political grabs. In some states, indeed, the difference would hardly, if at all, be felt. It is a racing certainty that in, say, Washington, California or New York abortion rights would remain much as they are – liberal. True, some other states might well want to pass more restrictive laws. It is hard to see the legislatures in states such as Mississippi, Arizona, or Arkansas, for example, doing anything other than rushing to introduce fairly draconian provisions, possibly exempting only direct threats to the life of the mother. But there is nothing wrong with that. It is always open to pro-choice activists argue against such laws: if they can persuade the voters that they are right, good for them. But if they can’t, then there is no reason why the law should not be different in Mississippi and California. That is democracy, and it should be given its head.

So, Senators, as regards the abortion issue, your way is clear. Whatever you think of events in Warsaw, support Amy Coney Barrett’s appointment to the Supreme Court. It’s the principled and constitutional thing to do.