The survival of Poland is one of the wonders of modern history. Powerful and ruthless neighbours repeatedly sought to partition and destroy it, yet from Nazi and Soviet tyranny, as well as earlier occupations, it has escaped, revived and flourished. Just as the historic heart of Warsaw was rebuilt after being reduced to rubble in the Second World War, so now national sovereignty has been regained after being crushed by Hitler and Stalin.

British politicians and diplomats were right to see, in the widening of the European Union to the east, a way of thwarting schemes of domination conceived in Brussels. Poland would not tolerate vassal status.

And yet the way in which the Polish government is just now asserting Polish sovereignty is highly regrettable. It has passed a law which imposes a criminal penalty of up to three years’ imprisonment for “public and contrary-to-fact conduct that attributes responsibility or co-responsibility for Nazi crimes committed by the Third German Reich to the Polish nation or the Polish state”.

The law is entirely unnecessary. No serious historian imagines the Polish nation or state requires such protection, for no serious historian supposes the Polish nation or state was responsible for the Holocaust.

On the contrary, it is generally recognised that Poland suffered abominably at the hands of the Nazis. References by foreigners such as Barack Obama to “Polish death camps”, to mean death camps erected on Polish soil, are insultingly slipshod, but do not mean Poland is being blamed for Nazi crimes.

The new law is additionally provocative because it grants exemptions to academics and artists, but not to journalists or teachers. What then will happen if a journalist or teacher refers to such events as the Jedwabne massacre of 1941, when Poles did indeed kill Jews?

The ruling Law and Justice Party passed this law in order to raise a storm of protest, against which it can then defend the embattled nation. Poland becomes the victim of international attack, with Israel, Ukraine, the United States and other foreign powers expressing outrage at the law, which in turn justifies xenophobic and anti-semitic responses from Poles.

This poisonous dynamic can do untold harm, notably to relations with Poland’s Jews, which have greatly improved in recent decades. But how, beyond issuing dignified protests, should Poles and friends of Poland respond to the new law?

For the EU, this is a particular difficulty, for if it condemns what Warsaw is doing, or indeed the provocations uttered by Viktor Orban in Budapest, it opens itself to the charge that Brussels itself is an appallingly undemocratic place, full of hypocritical officials with an inflated idea of their own worth, who imagine they have the right to tell democracies like Poland and Hungary how to behave.

It is no good brandishing a moral club at Poland, as if it were some errant schoolchild. The real argument against the new law is that it threatens to bring the Polish nation into disrepute. It is a law unworthy of one of the great, civilised nations of Europe.