The Courts of Mixed Commission

This illegal inflow could be effectively interrupted at one of three stages: at the point of dispatch of the captives in Africa, during their transatlantic voyage, or after their arrival in the Americas. Action in the first and the third phases ultimately hinged on public attitudes in the countries either sending or receiving captives. No country in the nineteenth century had the power to invade recalcitrant states and enforce abolition, if indeed "freedom" can ever be imposed by force. Interruption of the second phase, the transatlantic voyage, was both a diplomatic and a naval issue.

Punitive action on the high seas against foreign nationals required, first, the assent of the nation to which the offender belonged and, second, sufficient forces to make the action possible. The slave trade was by definition an international activity, and laws were still very much evolving in the early nineteenth century. Several nations, including Britain and the U.S., declared slave trading to be piracy, an offence in international waters which in theory any nation could suppress. But to this day the international community has never succeeded in prosecuting slave traders for piracy. Even if it had, it was always rare for one nation to put citizens of another on trial for piracy, much less to execute them.

The largest sweep against piracy that the British navy ever carried out was along the coast of Africa in 1721-22. They detained over two hundred pirates, many of them French. Ninety-one were condemned, fifty-four of whom were hung in batches at British forts distributed along the Gold Coast. Every one of the foreign nationals was released.

It was no different in the nineteenth century. The British, Dutch, Spanish, Portuguese, and several other minor maritime powers eventually set up bilateral courts to adjudicate ships suspected of slave trading. These were called Courts of Mixed Commission and were located at different times in Sierra Leone; Luanda, Angola; Cape Town, South Africa; Rio de Janeiro, Brazil; Paramaribo, Suriname; Kingston, Jamaica; and New York.

Such courts could confiscate vessels, equipment, and merchandise, as well as release captives, but could exact no penalties against crews or owners. Given that slave traders could often repurchase these items (except for the captives) at the subsequent prize auction, these provisions were not a huge deterrent. France (except for a short period), Sardinia (with strong links to Bahia, Brazil), and, until 1862, the United States would not even go this far. Like all other nations, they were prepared to arrest and try their own nationals, but would allow foreign powers (usually, in practice, Britain) only to hand over any suspects for adjudication in their own domestic courts.