Laws are essentially diffs against the US code. The diff (slip law) is canonical. They are continually compiled into the US code, which can involve deleting or changing text just like a diff, and periodically an edited, annotated code is published. After a certain amount of time, Congress enacts a portion of the published code, making it canonical and overriding any prior slip law.

See: http://en.wikipedia.org/wiki/United_States_Code#Legal_status

What we need now is software that reads bills ("in section 123.abc the text 'blah blah' is replaced by 'bleh bleh') and compiles it into before/after views of what the resulting code would be.

I just suggested this, and then scrolled down to find this.

Someone needs to take the plunge and start writing the program; throw it on Github and tell us all about it. I know people who are looking for such a tool.

Interesting: http://uscode.house.gov/codification/legislation.shtml

The US Code is not the same as the laws of the US. It is a "current snapshot" of existing laws in force, and does not itself have legal weight unless explicitly granted by Congress.

See, e.g., U.S. National Bank of Oregon v. Independent Insurance Agents of America, Inc., 508 U.S. 439, 440 (1993) for the Supreme Court's ruling and underlying logic.

According to Wikipedia:

"When sections are repealed, their text is deleted and replaced by a note summarizing what used to be there." https://en.wikipedia.org/wiki/United_States_Code#Treatment_o...

Imagine trying to keep track of this in paper form instead of digitally.

Imagine? I used to do it. When I first started out, I would get stacks of the Chicago Municipal Code revisions on onionskin and it was my job to follow the instructions to update the five-inch binder.

"Remove pages 123.4 - 123.6 and replace with pages 123.4a-123.7."

Later, when I learned about diffs, I understood the concept immediately.

They've been doing exactly that for about 237 years.