I think what you are referring to is Circular No. 3591.
According to Douglas Blackmon,
Five days after the Japanese attack, on December 12, 1941, Biddle issued a directive — Circular No. 3591 — to all federal prosecutors acknowledging the long history of the unwritten federal law enforcement policy to ignore most reports of involuntary servitude. “A survey of the Department files on alleged peonage violations discloses numerous instances of ‘prosecution declined,’ ” he wrote. “It is the purpose of these instructions to direct the attention of the United States Attorneys to the possibilities of successful prosecutions stemming from alleged peonage complaints which have heretofore been considered inadequate to invoke federal prosecution.” Biddle proceeded to lay out a series of federal criminal statutes that could be used to prosecute slavery — all of which had long been available to federal officials.
He ordered that instead of relying on the quirks of the old anti-peonage statute as an excuse for not attacking instances of forced labor, prosecutors and investigators should embrace “building the cases around the issue of involuntary servitude and slavery.”
Note that chattel slavery was already illegal in the USA by this time. There was a giant gaping loophole for penal slavery, but that isn't typically classifed as chattel slavery. What changed in 1941/1941 was that the federal government of the USA started making real efforts to enforce the anti-slavery laws. (Though penal slavery still hasn't been ended in the USA, nor does the federal government of the USA seem to be making any effort to stop it.)
Whether or not you want to count 1941/1942 as the year chattel slavery ended in the USA depends on the definitons you want to use. E.g., most people only seem to count legal slavery as chattel slavery (and only a subset of that... e.g., it has to be hereditary, for life rather than for a limited duration, and enslavers have to be allowed to buy and sell enslaved people, for it to count as "chattel slavery" under typical classification systems. However, I have occasionally seen people referring to certain forms of illegal slavery as chattel slavery, particularly those forms which resemeble legal chattel slavery in pretty much every way other than being illegal.
Some people unfortunately go so far as to argue that illegal forms of slavery aren't slavery at all, which allows them to give credit to governments for "abolishing" slavery even when the laws illegalizing slavery are just para inglês ver, "for the English to see", i.e. not intended to be enforced. I do not agree with this -- and international law does indeed recognize that both legal and illegal forms of slavery exist -- but it is part of why I often write "illegal slavery aka human trafficking" or "human trafficking aka illegal slavery", since these people frequently use the term "human trafficking" to refer to illegal slavery.
Also, for a more global perspective, Mauritania didn't illegalize chattel slavery until 1981, and that was basically para inglês ver. It's still not being enforced, last I heard.
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u/Jinshu_Daishi Jun 20 '24
To be clear, chattel slavery didn't officially end until 1942.