The Law Does Not Compel the Impossible

Lex non cogit ad impossibilia - the law does not compel the impossible. This centuries-old Roman maxim protects parties from liability when performance becomes objectively impossible through no fault of their own. Difficult is not impossible, and the distinction decides whether a defence holds.

Under FIDIC, relief comes through the force majeure or exceptional event clause, with notice due within 14 days of awareness. The first practical step is to fix the date of awareness and work out the notice deadline under your own form of contract.

The principle emerged from Roman jurisprudence as a safeguard against unjust obligations. It later migrated into English common law and from there into legal systems worldwide. Its core proposition is straightforward: the law should not require what cannot be done.

In contract law, the doctrine underpins the concepts of frustration and force majeure. The law does not hold the obligor to an impossible standard when:

• A contract is destroyed by natural disaster.
• Performance is rendered illegal by a change in law.
• Supervening events make the obligation fundamentally different from what was originally contemplated.

The distinction between difficult and impossible is critical. The doctrine does not excuse performance that is merely expensive, inconvenient, or commercially undesirable. It applies when performance is objectively impossible - not when it is subjectively unwelcome, and where the employer takes the opposite view the argument often comes back as a defence against liquidated damages. Courts have consistently drawn this line with precision.

In statutory interpretation, the principle guides how courts read legislative provisions. Where a statute appears to require the impossible, courts will interpret it in a manner that avoids absurdity - reading the provision purposively rather than literally to arrive at a result the legislature could have intended.

In administrative law, the doctrine constrains the exercise of government power. Administrative bodies cannot impose obligations that are incapable of performance. Where they attempt to do so, the courts have intervened - citing the maxim as both a principle of fairness and a limitation on authority.

Case law across jurisdictions reinforces the doctrine's vitality. The Indian Supreme Court in Raj Kumar Dey v. Tarapada Dey and State of Rajasthan v. Shamsher Singh, and the UK courts in Transfield Shipping Inc v. Mercator Shipping Inc, have each applied the principle to protect parties from obligations that had become impossible through circumstances beyond their control. It sits alongside other maxims that decide contractors' entitlements, from mutatis mutandis to contra proferentem, collected in our guide to legal maxims in construction contracts.

For contractors and contract managers, the relevance is direct. When force majeure events occur, when site conditions make performance impossible, when regulatory changes prohibit what was originally required, the law provides a defence. But that defence must be properly invoked, documented and communicated. The principle protects you. The discipline of contract administration activates that protection.