Can a sovereign have unlimited legal power? If a sovereign does have unlimited legal power, then the sovereign presumably has the legal power to limit or even completely abdicate its own legal power. But doing so would mean that the sovereign no longer has unlimited legal power, thereby contradicting the initial supposition. This theoretical conundrum is traditionally known as the paradox of omnipotence.

Social scientists have recognized that sovereign omnipotence can be a source of considerable practical difficulty for sovereigns themselves. Douglass North and Barry Weingast show that English and French monarchies in the seventeenth and eighteenth centuries confronted a practical challenge created by the paradox of their own omnipotence.

North and Weingast point out that it is often in a sovereign's best interest to make a credible commitment not to perform certain acts. For example, a sovereign with absolute power can refuse to honor its financial commitments. Yet creditors will not voluntarily lend generous amounts at favorable terms to an absolute monarch who can renege upon debts at will.

In the struggle to expand their empires, the English and French monarchies required vast amounts of capital. At the outset of the seventeenth century, however, neither regime could credibly commit itself to repay debts or to honor property rights. The absence of limitations upon the legal power of monarchs meant that there was no law or commitment monarchs could make that they could not also unmake or disregard. Consequently, these monarchs earned a reputation for expropriating wealth, repudiating debts, and reneging upon commitments. Not surprisingly, creditors took such behavior into account and demanded higher interest rates from monarchs than from the monarchs' wealthy subjects.

North and Weingast argue that the constitutional settlement imposed in England by the Glorious Revolution of 1688 halted such faithless conduct. Henceforth, Parliament controlled the Crown's purse strings. Parliament, in turn, represented commercial interests that would not tolerate governmental disregard for property rights. The Crown's newfound inability to dishonor its commitments translated into a newfound ability to borrow: the Crown's borrowing increased and interest rates fell, because lenders concluded that the Crown would honor its debts.

Thanks to North, Weingast, and others writing in the same vein, it is now conventional to hold that constitutional arrangements benefit sovereigns by limiting their power. But such scholars neglect the extent to which constitutions can fail in this regard. For example, the constitutional settlement imposed by the Glorious Revolution did not solve the paradox of omnipotence but just relocated the problem from one branch of government to another: whereas it was once the Crown that lacked the power to bind itself, it is now Parliament that lacks this power. The doctrine of parliamentary sovereignty is a pillar of England's unwritten constitution, and it provides that Parliament lacks legal power over the extent of its own legal power.