Although there is widespread recognition of racial bias in US law, it is unclear how such bias appears in the language of law, namely judicial opinions, and whether it varies across time period or region. Building upon approaches for measuring implicit racial bias in large-scale corpora, we approximate GloVe word embeddings for over 6 million US federal and state court cases from 1860 to 2009. We find strong evidence of racial bias across nearly all regions and time periods, as traditionally Black names are more closely associated with pre-classified "unpleasant" terms whereas traditionally White names are more closely associated with pre-classified "pleasant" terms. We also test whether legal opinions before 1950 exhibit more implicit racial bias than those after 1950, as well as whether opinions from Southern states exhibit less change in racial bias than those from Northeastern states. We do not find evidence of elevated bias in legal opinions before 1950, or evidence that legal opinions from Northeastern states show greater change in racial bias over time compared to Southern states. These results motivate further research into institutionalized racial bias.

翻译：尽管美国法律中种族偏见的普遍存在已获广泛认可，但此类偏见在法律语言（即司法意见）中的表现形式及其是否随时期或地域变化尚不明确。基于大规模语料库中隐性种族偏见的测量方法，我们对1860年至2009年间超过600万份美国联邦及州法院案件近似构建了GloVe词嵌入。研究发现，几乎所有地区和时期都存在强烈的种族偏见证据：传统黑人姓名与预先分类的"不愉快"术语关联更紧密，而传统白人姓名则与预先分类的"愉快"术语关联更密切。我们还检验了1950年前法律意见是否比1950年后表现出更强的隐性种族偏见，以及南方州法律意见的种族偏见变化是否小于东北部州。结果未发现1950年前法律意见存在更高偏见的证据，也未发现东北部州法律意见的种族偏见随时间变化程度显著大于南方州。这些结果为进一步研究制度性种族偏见提供了依据。