Maxims on property, contracts and knowledge

The essentials

Many everyday transactions are guided by maxims. They decide who bears the risk in a sale, whether a buyer gets good title, what makes an agreement real, and whether a person can plead ignorance of the law. Some maxims are also used in taxation and constitutional law.

Key points

• Caveat emptor: "let the buyer beware" – the buyer must examine goods before buying; the seller is not generally responsible for defects, subject to exceptions under the Sale of Goods Act, 1930 (for example, fraud or sale by description).
• Nemo dat quod non habet: "no one gives what he does not have" – a seller cannot pass better title than he has. A buyer of stolen goods does not become the owner.
• Bona fide: "in good faith" – honestly, without fraud. A bona fide purchaser buys honestly and for value.
• Bona vacantia: "ownerless goods" – property without an owner, such as the estate of a person who dies without heirs, passes to the State (Article 296 in India).
• Quid pro quo: "something for something" – the idea of consideration in contracts.
• Assensus mentium (consensus ad idem): "meeting of minds" – both parties must agree on the same thing in the same sense.
• Ignorantia juris non excusat: "ignorance of the law is no excuse". (Ignorance of fact may be an excuse.)
• Ad valorem: "according to value" – a tax or duty calculated as a percentage of value.
• De minimis non curat lex: "the law does not concern itself with trifles" – very minor matters are not taken up by courts.
• Ex post facto: "after the fact" – a law with retrospective effect. Article 20(1) bars ex post facto criminal laws.

Exam tips

• Contrast ignorance of law (no excuse) with ignorance of fact (may be an excuse).
• Link quid pro quo with consideration and assensus mentium with consent.

Common mistakes

• Confusing bona fide (good faith) with bona vacantia (ownerless property).
• Thinking ex post facto civil or tax laws are always banned – Article 20(1) applies to criminal laws.