The article introduces innovative means by which states can express their consent to be bound by treaties. Such innovative means have been incorporated in some multilateral environmental agreements that were concluded in December 1999 and January 2000. It is discussed whether limits of law-making have been transgressed by the use of these innovative means as the law of treaties allegedly presupposes that states actually give their consent to new treaty obligations, take some active step to express their consent to such obligations and do so at a time that the obligations were in existence and were known to them.