Lawrence Lessig has taken some time to explain the nuances of his arguments in the Eldred Supreme Court case and of the judges' reaction. For many followers of the case, Eldred was an introduction to the workings of the Supreme Court, and we've been scratching our heads and speculating wildly as to what Larry said and what the judges said and what the opposing counsel said and what it all meant. Larry's primer on judge-counting and Supreme shenanigans is just what we needed to make sense of it all:
The government then helped us immensely by simply confirming what we had said: under their theory of the case, there was no constitutional limit on Congress's power to extend terms; it was always a matter of Congress's discretion. Congress could perpetually extend existing terms; it could even extend a copyright to works within the public domain.
The Court clearly did not like this answer. They had bought the idea that the Constitution intended there to be a limit; the government's interpretation meant that this was a limit that was solely a matter of legislative grace. (Compare: "Under our written Constitution the limitation of congressional authority is not solely a matter of legislative grace.") They were not comfortable with the idea that they would simply say that though the constitution expressly limits Congress's power, it is Congress that gets to say what that limit is.