69. ~The Struggle for an International Right of Search, 1820-1840.~ Whatever England's motives were, it is certain that only a limited international Right of Visit on the high seas could suppress or greatly limit the slave-trade. Her diplomacy was therefore henceforth directed to this end. On the other hand, the maritime supremacy of England, so successfully asserted during the Napoleonic wars, would, in case a Right of Search were granted, virtually make England the policeman of the seas; and if nations like the United States had already, under present conditions, had just cause to complain of violations by England of their rights on the seas, might not any extension of rights by international agreement be dangerous? It was such considerations that for many years brought the powers to a dead-lock in their efforts to suppress the slave-trade. At first it looked as if England might attempt, by judicial decisions in her own courts, to seize even foreign slavers.[25] After the war, however, her courts disavowed such action,[26] and the right was sought for by treaty stipulation. Castlereagh took early opportunity to approach the United States on the matter, suggesting to Minister Rush, June 20, 1818, a mutual but strictly limited Right of Search.[27] Rush was ordered to give him assurances of the solicitude of the United States to suppress the traffic, but to state that the concessions asked for appeared of a character not adaptable to our institutions. Negotiations were then transferred to Washington; and the new British minister, Mr. Stratford Canning, approached Adams with full instructions in December, 1820.[28]