After the Override: An Empirical Analysis of Shadow Precedent
本研究首次实证检验国会推翻司法解释后，被推翻判例的引用量下降远少于司法推翻，且修复性推翻后引用下降更快，表明影子先例持续存在更多源于信息失败或模糊性而非意识形态分歧。
Congressional overrides of prior judicial interpretations of statutory language are typically defined as equivalent to judicial overrulings, and they are presumed to play a central role in maintaining legislative supremacy. Our study is the first to empirically test these assumptions. Using a differences-in-differences research design, we find that citation levels decrease far less after legislative overrides than after judicial overrulings. This pattern holds true even when controlling for depth of the superseding event or considering only the specific proposition that was superseded. Moreover, contrary to what one might expect, citation levels decrease more quickly after restorative overrides—in which Congress repudiates the prior Supreme Court decision as incorrect—than after overrides intended to update or clarify the law. This suggests that ongoing citation of overridden precedents, what we call shadow precedents, may be driven more by information failure or ambiguity than by ideological disagreements between the branches of government.