Even such spasmodic efforts bore abundant fruit, and indicated what vigorous measures might have accomplished.  Between May, 1818, and November, 1821, nearly six hundred Africans were recaptured and eleven American slavers taken.[136] Such measures gradually changed the character of the trade, and opened the international phase of the question.  American slavers cleared for foreign ports, there took a foreign flag and papers, and then sailed boldly past American cruisers, although their real character was often well known.  More stringent clearance laws and consular instructions might have greatly reduced this practice; but nothing was ever done, and gradually the laws became in large measure powerless to deal with the bulk of the illicit trade.  In 1820, September 16, a British officer, in his official report, declares that, in spite of United States laws, “American vessels, American subjects, and American capital, are unquestionably engaged in the trade, though under other colours and in disguise."[137] The United States ship “Cyane” at one time reported ten captures within a few days, adding:  “Although they are evidently owned by Americans, they are so completely covered by Spanish papers that it is impossible to condemn them."[138] The governor of Sierra Leone reported the rivers Nunez and Pongas full of renegade European and American slave-traders;[139] the trade was said to be carried on “to an extent that almost staggers belief."[140] Down to 1824 or 1825, reports from all quarters prove this activity in slave-trading.

The execution of the laws within the country exhibits grave defects and even criminal negligence.  Attorney-General Wirt finds it necessary to assure collectors, in 1819, that “it is against public policy to dispense with prosecutions for violation of the law to prohibit the Slave trade."[141] One district attorney writes:  “It appears to be almost impossible to enforce the laws of the United States against offenders after the negroes have been landed in the state."[142] Again, it is asserted that “when vessels engaged in the slave trade have been detained by the American cruizers, and sent into the slave-holding states, there appears at once a difficulty in securing the freedom to these captives which the laws of the United States have decreed for them."[143] In some cases, one man would smuggle in the Africans and hide them in the woods; then his partner would “rob” him, and so all trace be lost.[144] Perhaps 350 Africans were officially reported as brought in contrary to law from 1818 to 1820:  the absurdity of this figure is apparent.[145] A circular letter to the marshals, in 1821, brought reports of only a few well-known cases, like that of the “General Ramirez;” the marshal of Louisiana had “no information."[146]