These depressing views by the eminent international lawyers, Hersch Lauterpacht and O'Connell in 1953 and 1970, respectively, are even truer today. The last word had not been said in Articles 19–23. As is apparent from the vast amount which has been written on the subject, a spirited debate has developed on how those articles should be applied, especially the effect of an objection to a reservation on the ground that it is contrary to the object and purpose of the treaty: an issue seen as particularly relevant to human rights treaties.

It would be wrong to think that the problems are just theoretical. Since the Second World War, and especially during the last quarter of the twentieth century, there has been an enormous increase in the number and complexity of multilateral treaties on all subjects, and in the number of states adhering to them. In 1945, the United Nations had fifty-one Members; by the end of 2006, it had 192. In the twenty years from 1975 to 1995 just one state, the United Kingdom, became a party to some 330 multilateral treaties, and made reservations to forty-five of them. Every week foreign ministries will be notified of new reservations. They will have to consider whether they are acceptable and, if not, what to do about them.