Git for the US Code

A programmer can point at any line of code and see who wrote it, when, and what the file looked like on any past day. A lawyer reading a federal statute usually cannot, at least not without an afternoon in the notes at the foot of the section. But why shouldn’t they have the same, convenient system of record? It is especially relevant given that so much first-pass legal research now runs through language models, which are often unable to utilise the proper lineage of a law, handcuffing its ability to offer interpretation.

程序员可以指出任何一行代码，查看是谁在何时编写的，以及该文件在过去任何一天的样子。而阅读联邦法规的律师通常做不到这一点，除非花一下午时间去查阅章节底部的注释。但他们为什么不能拥有同样便捷的记录系统呢？鉴于目前大量的初步法律研究都是通过语言模型进行的，而这些模型往往无法利用法律的正确渊源，从而限制了其提供解释的能力，这一点显得尤为重要。

Outside the titles Congress has enacted as positive law, the code is only prima facie evidence of the law, and the Statutes at Large govern where the two differ.[1] The Office of the Law Revision Counsel publishes it as a series of release points, each current through a named public law, and keeps reorganising it; a bill to enact title 41 as positive law was introduced in September 2025.[2] Which public law wrote a sentence is recorded in amendment notes, in prose. When a change took effect is often in a separate effective-date note, and where Congress said nothing the default rule is that a law takes effect on the day it is enacted.[3]

在国会颁布为积极法（positive law）的法典标题之外，法典仅作为法律的初步证据，若两者存在差异，则以《美国法律总汇》（Statutes at Large）为准。[1] 法律修订顾问办公室将其作为一系列发布点进行发布，每个发布点均更新至特定的公法，并不断进行重组；一项将第41编制定为积极法的法案已于2025年9月提出。[2] 某一句法律是由哪项公法编写的，记录在散文形式的修正案注释中。变更何时生效通常在单独的生效日期注释中说明，如果国会未作说明，默认规则是法律自颁布之日起生效。[3]

The definition of a small business debtor in 11 USC § 1182(1) shows how far apart those answers can be. It was created in 2019 with the existing small business debt limit.[4] The CARES Act raised the limit to $7.5 million in March 2020 as a temporary measure, later extended to March 2022.[5],[6] That increase lapsed on 27 March 2022, and on 21 June 2022 Congress restored it for two more years, for cases commenced on or after 27 March 2020 and still pending, which reached back over the gap.[7] The higher limit expired again in June 2024, and after the triennial adjustment in April 2025 it stands at $3,424,000.[8],[9] For a case filed in May 2022, the release point printed at the time gives the lower limit, and only a later Act changes the answer. A history that is useful to a lawyer has to carry the text, the date each change took force, and the scope of any law that reaches back.

《美国法典》第11编第1182(1)条中关于小企业债务人的定义，展示了这些答案之间的差异有多大。该定义于2019年创建，采用了当时的小企业债务限额。[4] 《CARES法案》在2020年3月将该限额提高到750万美元作为临时措施，后来延长至2022年3月。[5],[6] 该增长于2022年3月27日失效，国会于2022年6月21日将其恢复了两年，适用于2020年3月27日或之后开始且仍在审理中的案件，这实际上追溯到了之前的空窗期。[7] 更高的限额在2024年6月再次到期，经过2025年4月的三年期调整后，限额为3,424,000美元。[8],[9] 对于2022年5月提交的案件，当时打印的发布点显示的是较低的限额，只有后来的法案才改变了答案。对律师有用的历史记录必须包含文本、每次变更生效的日期，以及任何具有追溯力法律的适用范围。

A study from the Technical University of Munich this year found two failures in models answering questions on German statutes: they apply rules that were superseded after their training cutoff, and they prefer the newer provision even when an older one governs the facts. One model answered 24% of post-cutoff questions correctly on its own and 87% when the relevant statutory text was retrieved for it, and the authors conclude that temporal validity has to be treated as a hard constraint.[10] Other recent work trains search agents to respect the date a question is about, with large gains in consistency.[11]

慕尼黑工业大学今年的一项研究发现，模型在回答有关德国法规的问题时存在两个缺陷：它们应用了在训练截止日期后已被废止的规则，并且即使在旧条款适用于事实的情况下，它们也倾向于使用新条款。一个模型在没有辅助的情况下仅正确回答了24%的截止日期后的问题，而在检索到相关法规文本后，正确率达到了87%。作者得出结论，时间有效性必须被视为一项硬性约束。[10] 其他近期研究通过训练搜索代理来尊重问题所涉及的日期，从而在一致性方面取得了巨大进步。[11]

Asking a model to produce the old text does not solve this. When the same Munich group had a model apply German amending laws to earlier versions, the output looked 93–99% similar to the official text, but only half of single amendments and a fifth of chains of amendments matched exactly, and experts found legally significant errors in the near misses.[12] The history has to be checkable.

要求模型生成旧文本并不能解决这个问题。当同一个慕尼黑研究小组让模型将德国修正法应用于早期版本时，输出结果看起来与官方文本有93-99%的相似度，但只有一半的单一修正案和五分之一的修正案链完全匹配，专家在那些“几乎正确”的结果中发现了具有法律意义的错误。[12] 历史记录必须是可核查的。

For each pair of release points from 2017 onward, we took the public laws enacted in between, carried out their amending instructions on the older text in date order, and compared the result with the newer version. Of 365 changes across the nine titles, 361 reproduced the next release point exactly. The other four are shown with a label saying how far they could be confirmed. Each change then carries the law and the date it took effect: 261 took effect on enactment by default, 72 by an effective-date note and 29 by a date in the amendment itself. One depends on an agency determination that may never come, and we leave it out of the text rather than guess.

对于2017年以来的每一对发布点，我们提取了期间颁布的公法，按日期顺序对旧文本执行了它们的修订指令，并将结果与新版本进行了比较。在九个法典标题的365处变更中，有361处完全复现了下一个发布点。其余四处则标注了其可确认的程度。每项变更都附带了法律依据和生效日期：261项默认自颁布之日起生效，72项根据生效日期注释生效，29项根据修正案本身的日期生效。其中一项取决于可能永远不会到来的机构裁定，我们将其排除在文本之外，而不是进行猜测。

With that record, the reader can answer the questions lawyers ask. You pick a date and get the text in force on it, with the words that read differently today marked. Each phrase is coloured by the Act that wrote it. A change to a defined term lists every other provision that uses it, and you can follow a section to see what has changed since your last visit.

有了这些记录，读者就可以回答律师们提出的问题。你可以选择一个日期，获取当时生效的文本，并标记出与今天表述不同的词汇。每个短语都根据编写它的法案进行了颜色标注。对定义术语的更改会列出所有使用该术语的其他条款，你可以跟踪一个章节，查看自上次访问以来发生了什么变化。

It does not yet show a later law’s reach back on the earlier dates it covers, so for a case filed in the 2022 gap it shows the lower limit without warning that the June 2022 Act changed the answer.

它目前尚未显示后续法律对其涵盖的早期日期的追溯影响，因此对于2022年空窗期提交的案件，它显示的是较低的限额，而没有警告说2022年6月的法案已经改变了答案。

Effective-date notes are read by pattern, and unusual wording falls back to the date of enactment.

生效日期注释是按模式读取的，不寻常的措辞则回退到颁布日期。

Each change links to the law’s own words, and for anything that matters the original should be read.

每一项变更都链接到法律本身的原文，对于任何重要事项，都应阅读原始文件。

We’re also still thinking about the right form factor this should take.

我们仍在思考这应该采取什么样的正确表现形式。