THEY WRITE MUSICALS about it in the US; swear by it in Canada; swear about it in Australia; and use as it as a weapon in Sri Lanka. Constitutions matter. But right now they seem troublingly fragile. Governments impose states of exception at will. Basic legal norms are under attack. Authoritarian populists mount brazen assaults on judicial independence, the rule of law and human rights. What difference can a document from another era make?

Constitutions are not just legal structures. They are ‘soft power’. In other countries, constitutional courts have from time to time been prepared to articulate a broader vision of democratic rights and legal values. These visions are not just reliant on written bills of rights. They also draw on underlying legal principles that give those texts a deeper meaning – the inaugural president of the Hungarian Constitutional Court called it the ‘invisible constitution’. Many Australians think of our constitution as little more than a division of power. But where does its legitimacy come from, and what does it stand for?