A more thorough explanation:

LEX MONETAE

Lex monetae is a Latin term that refers to the law of the country whose currency is being used in a transaction.

When two parties from different countries engage in a transaction, the law that governs the transaction is determined by the country whose currency is being used. For example, if a person from the United States buys goods from a person in Japan using Japanese yen, the law that governs the transaction is Japanese law because the currency being used is yen.

Suppose a person from the United States buys a product from a person in Canada using Canadian dollars. In this case, the law that governs the transaction is Canadian law because the currency being used is Canadian dollars.

Another example is when a person from Germany buys a product from a person in France using euros. In this case, the law that governs the transaction is French law because the currency being used is euros.

These examples illustrate how lex monetae works in practice. The law that governs a transaction is determined by the country whose currency is being used, regardless of the nationality or location of the parties involved.