Britain spent years arguing about whether membership of the European Union had taken too much sovereignty away from Parliament. Eventually, British voters chose to leave.
Poland is now creating a different and potentially more difficult problem.
It does not want to leave.
It wants to remain inside while challenging one of the principles that makes membership work.
On Thursday, Poland’s Constitutional Tribunal ruled that parts of European Union law are incompatible with the Polish Constitution. The decision came after Prime Minister Mateusz Morawiecki asked the court to examine the relationship between Polish constitutional law and EU law amid a much wider dispute between Warsaw and Brussels over changes to Poland’s judiciary.
The Polish government argues that Poland remains a sovereign country and that its constitution must therefore remain the highest source of law inside Poland. From that perspective, the argument sounds almost obvious. Why should judges outside Poland possess greater authority than Poland’s own constitution?
The European Union’s answer is equally fundamental. Poland voluntarily joined a legal order in which common European rules have to apply consistently across member states. If every national government can simply declare inconvenient EU rules unconstitutional, then European law stops being meaningfully European.
That makes this much more than another argument between Brussels and a conservative Polish government.
It is an argument about what the European Union actually is.
Is it an organisation of sovereign states cooperating when they choose?
Or is it a political and legal system in which member states have voluntarily transferred enough authority that some decisions bind them even when their governments disagree?
The EU has always contained elements of both.
This week demonstrates how difficult that ambiguity becomes when the two principles collide.
Poland joined the European Union in 2004. Membership has transformed the country’s economic and political position. Poland gained access to the single market and became one of the largest recipients of EU funding. Polish citizens gained extensive rights to live and work elsewhere in the Union. Membership also embedded Poland more deeply within Western European political institutions after decades inside the Soviet sphere of influence.
Support for EU membership remains very high among Polish citizens.
That is why describing the current dispute simply as “Polexit” may be misleading.
Britain’s Brexit debate eventually became a question of membership itself. Poland’s governing Law and Justice party says it wants Poland to remain in the EU.
The conflict is instead over the conditions of membership.
Warsaw’s position is effectively that joining the European Union did not mean surrendering ultimate constitutional sovereignty.
Brussels responds that Poland did not surrender sovereignty. It exercised sovereignty by signing treaties that created binding obligations.
That distinction is fascinating because it changes what sovereignty means.
We normally imagine sovereignty as freedom: a sovereign country can decide what it wants.
But treaties transform sovereignty into something more complicated.
Suppose two countries voluntarily sign an agreement saying neither will impose tariffs on the other’s goods. Tomorrow, Country A decides it wants a tariff.
Can it simply say, “We are sovereign, so the agreement cannot restrict us”?
In one sense, yes. No treaty can physically prevent a government from violating it.
But if sovereignty meant governments could disregard every commitment whenever it became inconvenient, international agreements would be almost worthless.
The ability to make a binding promise is itself a form of sovereignty.
So perhaps the relevant question is not whether Poland remains sovereign. Of course it does.
The question is which constraints Poland previously agreed to place upon the exercise of that sovereignty when it joined the EU.
That is much harder.
The dispute becomes even more complicated because it is not really occurring in a vacuum. It emerged from a long confrontation over Poland’s judiciary.
Since taking power in 2015, the Law and Justice government has introduced extensive judicial reforms. It argues that Poland’s courts needed reform because they were inefficient and insufficiently accountable, and that unelected judges should not be able to prevent an elected government from implementing its programme.
Critics inside Poland and across the EU argue that the reforms weaken judicial independence by increasing political influence over appointments and disciplinary procedures.
That disagreement matters because Thursday’s ruling came from the very constitutional system whose independence is being questioned.
This creates a problem of institutional credibility.
If a completely independent constitutional court ruled against the European Union, Brussels would still disagree with the legal conclusion.
But when critics believe the government has already compromised the independence of that court, the ruling looks less like an ordinary constitutional judgement and more like one branch of the Polish state reinforcing another.
This is why judicial independence can feel incredibly abstract until a political crisis occurs.
Courts do not need to be politically neutral because judges somehow possess no personal opinions. That would be impossible.
They need enough institutional independence that citizens believe decisions are being made through law rather than instructions from whichever party currently governs.
The distinction matters most when the court rules in the government’s favour.
A government naturally insists the ruling is independent.
Its opponents naturally suspect political influence.
Only strong institutions can make both sides accept the outcome anyway.
This dispute also exposes a tension at the centre of democratic politics.
Law and Justice won elections.
Its supporters can therefore reasonably ask why unelected judges in Warsaw or Luxembourg should be able to block policies chosen by an elected government.
That argument has considerable democratic force.
But democracy cannot simply mean that whoever wins an election can change every institution.
Elections determine who governs temporarily. Constitutions and courts establish limits on what temporary majorities can do.
Otherwise a government can win one election, weaken the institutions capable of challenging it and then make future political competition increasingly unequal.
This is the same distinction I have encountered repeatedly this year: majoritarianism is not identical to democracy.
A majority gives governments authority.
Liberal democracy also places constraints on that authority.
Poland’s dispute with the EU is partly an argument over who gets to enforce those constraints.
And Brussels possesses an extraordinarily powerful instrument: money.
Poland is due to receive tens of billions of euros through the EU’s pandemic recovery programme. Approval of those funds has become entangled with concerns over the rule of law.
This is where a constitutional argument becomes an economic one.
The European Union can say: if you want access to common European funds, you must comply with common European rules.
Poland can respond: using money to force changes in domestic constitutional arrangements is political coercion.
Both descriptions contain something true.
Conditionality is coercive.
That is why it works.
But almost every agreement containing conditions is coercive in that broad sense. A bank lends money on conditions. The IMF provides financing on conditions. Trade agreements provide market access on conditions.
The important question is whether the conditions are legitimate and whether they were agreed in advance.
EU membership provides benefits precisely because countries accept obligations in return.
A system in which governments receive all the benefits while rejecting whichever obligations become politically inconvenient would probably not survive for long.
But Brussels also has to be careful.
If the EU increasingly uses financial pressure to determine how domestic institutions should operate, critics can plausibly argue that European integration has moved far beyond economic cooperation.
That may be exactly what committed European federalists want.
It may not be what every European voter believes they signed up for.
This is the deeper constitutional problem.
The European Union is not quite a country.
But it is considerably more than an ordinary international organisation.
The United Nations cannot normally tell India how the Indian Supreme Court must interpret the Constitution.
The European Court of Justice can issue rulings that directly affect national legal systems across the EU.
The EU has a parliament, court, executive institutions, currency for many members, common regulations, budget and enormous authority over trade.
Yet its citizens still primarily identify politically through national democracies, and national governments remain extraordinarily powerful.
Europe has therefore created something historically unusual: shared sovereignty without a fully shared state.
That works remarkably well when everyone broadly agrees.
Poland demonstrates what happens when they don’t.
If Polish law conflicts with European law, somebody has to possess the final word.
There cannot logically be two supreme legal authorities in the same area at the same moment.
Warsaw says the Polish Constitution.
The EU legal order says EU law within the powers established by the treaties.
That is not a disagreement that can be solved simply by asking both sides to compromise halfway.
One rule eventually has to prevail.
There is also a geopolitical dimension that makes the dispute particularly strange.
Poland is one of Europe’s most strongly anti-Russian states. Its history gives Warsaw profound reasons to fear Russian power, and Poland depends heavily on NATO and broader Western institutions for security.
Weakening Poland’s relationship with the European Union therefore creates strategic costs that neither Warsaw nor Brussels should want.
The Polish government wants greater national sovereignty partly because Poland spent so much of its history having sovereignty constrained by larger powers.
But the institutions it is challenging are also part of the Western political order that protects Polish sovereignty today.
That creates a paradox.
Poland joined NATO and the EU partly because embedding itself in larger institutions made the country safer and more prosperous.
Those same institutions necessarily restrict complete freedom of action.
Security and sovereignty therefore do not always move together.
Sometimes a country gives up some freedom to obtain more effective power.
This is true far beyond Europe.
India participates in the World Trade Organization, which constrains some trade policies but gives India rights against other countries in return. NATO members accept collective obligations because those obligations make each member safer. Countries sign investment treaties because accepting limits on their own behaviour encourages others to invest.
International cooperation is fundamentally an exchange of autonomy.
You accept restrictions on yourself because everyone else accepts restrictions too.
That is why Poland’s challenge matters to the entire European Union.
If Poland can decide that European law does not apply whenever its constitutional court disagrees, Germany can eventually make the same argument. So can France, Hungary or Italy.
At that point the single legal order begins becoming a menu.
Governments follow European rules when convenient and invoke national sovereignty when they are not.
The benefits of cooperation remain collective.
The obligations become optional.
That arrangement is unlikely to be stable.
But the opposite extreme would also create problems. If EU law always overrides national constitutional identity in every imaginable area, member states risk becoming administrative units inside a European state that their populations never explicitly agreed to create.
European integration therefore depends on an extraordinarily delicate bargain.
Enough common authority to make common rules credible.
Enough national autonomy to keep democratic legitimacy rooted in member states.
Poland is testing where that boundary actually lies.
I don’t think the answer is that Poland should leave the European Union. Most Poles apparently do not want that, and neither does their government.
Nor do I think Brussels can simply accept the tribunal’s ruling as an ordinary expression of national sovereignty.
The EU cannot operate as a common legal system if participation in that legal system becomes voluntary whenever national governments lose a case.
The more sustainable answer has to involve something harder: clearly distinguishing which powers member states genuinely transferred to the European level and protecting national constitutional authority everywhere else.
But that requires something currently in short supply.
Trust.
Poland has to trust that European institutions will not continuously expand their authority into areas never meaningfully transferred to them.
Brussels has to trust that Poland will not use constitutional sovereignty as a mechanism for escaping obligations it voluntarily accepted.
And both need citizens to trust that judges are interpreting rules rather than simply advancing the political objectives of whichever side appointed them.
Without that trust, every legal disagreement becomes a sovereignty crisis.
Brexit asked whether a country could recover sovereignty by leaving the European Union.
Poland is asking a much more complicated question:
How much sovereignty can you keep after choosing to stay?
Perhaps the answer is that membership does not eliminate sovereignty at all. It changes how sovereignty is exercised.
A country acting completely alone possesses maximum formal freedom but limited ability to influence what other countries do. A country inside a powerful union accepts constraints on its own choices but gains influence over rules affecting hundreds of millions of people.
Neither arrangement is automatically more sovereign.
They represent different kinds of power.
The real political choice is therefore not between sovereignty and no sovereignty.
It is between autonomy and influence, and deciding how much of one a country is willing to exchange for the other.
Poland made that exchange when it joined the European Union in 2004.
This week, it began arguing over the exchange rate.
