I am another of those who feel that the options should have included lifetime of the author/creator. That or 10-20 years with as many renewals as the author wishes in his lifetime. This it to explain my pick from the options offered of 50+ years; that being too long in some cases and not long enough in others. Having a public referendum to nullify? Yeah sure leave it to a vote as to whether or not an author has any intellectual rights.
I have to strongly disagree, as others have, that what was said in the United States Constitution on the issue is no longer valid for United States law. The Constitution is still the preeminent law of the land.
The current ridiculous state of copyright law in the United States, lifetime plus 70 years, is really all about the undue influence of corporate lobbying. M-I-C … K-E-Y … M-O-U-S-E.
Final comment on this whole topic being raised again. There are a significant number here that just do not accept the idea of intellectual property rights.