The burden of proof was laid on the defendant, to the extent that he must prove that the slave in question had been imported at least five years before the prosecution.  The slaves were still left to the disposal of the States.

This statute was, of course, a failure from the start,[114] and at the very next session Congress took steps to revise it.  A bill was reported in the House, January 13, 1819, but it was not discussed till March.[115] It finally passed, after “much debate."[116] The Senate dropped its own bill, and, after striking out the provision for the death penalty, passed the bill as it came from the House.[117] The House acquiesced, and the bill became a law, March 3, 1819,[118] in the midst of the Missouri trouble.  This act directed the President to use armed cruisers on the coasts of the United States and Africa to suppress the slave-trade; one-half the proceeds of the condemned ship were to go to the captors as bounty, provided the Africans were safely lodged with a United States marshal and the crew with the civil authorities.  These provisions were seriously marred by a proviso which Butler of Louisiana, had inserted, with a “due regard for the interests of the State which he represented,” viz., that a captured slaver must always be returned to the port whence she sailed.[119] This, of course, secured decided advantages to Southern slave-traders.  The most radical provision of the act was that which directed the President to “make such regulations and arrangements as he may deem expedient for the safe keeping, support, and removal beyond the limits of the United States, of all such negroes, mulattoes, or persons of colour, as may be so delivered and brought within their jurisdiction;” and to appoint an agent in Africa to receive such Negroes.[120] Finally, an appropriation of $100,000 was made to enforce the act.[121] This act was in some measure due to the new colonization movement; and the return of Africans recaptured was a distinct recognition of its efforts, and the real foundation of Liberia.

To render this straightforward act effective, it was necessary to add but one measure, and that was a penalty commensurate with the crime of slave stealing.  This was accomplished by the Act of May 15, 1820,[122] a law which may be regarded as the last of the Missouri Compromise measures.  The act originated from the various bills on piracy which were introduced early in the sixteenth Congress.  The House bill, in spite of opposition, was amended so as to include slave-trading under piracy, and passed.  The Senate agreed without a division.  This law provided that direct participation in the slave-trade should be piracy, punishable with death.[123]

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