As a one-time student of constitutional law, I remember all too well the shocking hypothetical scenarios lecturers loved to propose. For example, what if Parliament passed a law requiring all blue-eyed babies to be killed at birth? It is absurd, horrifying, and – crucially – impossible in practice. This one stuck with me, thanks to my lecturer, the inimitable Jeff Murray, who used it to illustrate just how extreme parliamentary sovereignty can be. As AV Dicey once observed, legislators “must go mad before they could pass such a law, and subjects be idiotic before they could submit to it.”
The so-called “blue-eyed baby statute” isn’t just a grim thought experiment. It exposes a core principle of UK constitutional law: Parliament is legally sovereign. No court can strike down a primary Act, and the monarch’s role in granting Royal Assent is purely ceremonial.
King Charles III, no matter how outraged, could only watch, quill trembling over vellum, as a law he despised became binding. Royal Assent exists not to give the sovereign discretion, but to preserve the monarchy by ensuring the Crown obeys Parliament, even when conscience recoils.
Contrast that with Monaco, where the sovereign still wields real legislative power. Earlier this month, Prince Albert II refused to sign a bill legalising abortion, halting legislation despite overwhelming parliamentary support. Monaco’s constitution explicitly grants the Prince the right to withhold ‘promulgation’ – a rare but entirely legal exercise of conscience. Across Europe, very few monarchs retain similar influence. Belgium’s King Baudouin refused to sign an abortion law in 1990, Luxembourg amended its constitution after Grand Duke Henri blocked a euthanasia bill in 2008, and Liechtenstein’s Prince Hans-Adam II has publicly said he would veto any abortion reforms. Monaco is a modern exception, where a single individual can still reshape the law.
The blue-eyed baby thought experiment shows the limits of power in practice. While Parliament in the UK is legally supreme, its authority is constrained by ethics and public opinion. Legislators may theoretically be able to pass extreme laws, but doing so would be self destruction. Dicey’s scenario highlights the tension between law and morality.
These examples reveal how differently constitutional systems handle power. In the UK, parliamentary sovereignty is absolute on paper, but tempered by elections and public accountability. In Monaco, the Prince is constitutionally empowered to intervene, embedding his own idea of conscience directly into law-making. Both systems rely on checks beyond the law itself: public opinion, ethical norms, and the opinions of those in power.
Ultimately, the blue-eyed baby statute is more than a classroom exercise. It reminds us that laws may be technically absolute, but morality, conscience, and institutional safeguards define the boundaries of legitimate authority. In the UK, the monarch obeys to preserve the institution; in Monaco, the sovereign may act to ‘protect’ it – yet in both cases, it is the balance between law and ethics that really matters.
