Musing on conspiracy theories & the 16th Amendment

At the suggestion/request of a student, I watched the Zeitgeist video yesterday. One of many of the conspiracy theories set forth in the video is that the Federal Income Tax is unconstitutional because the 16th Amendment was not properly ratified. So today I did a little looking on the internet to find out what the argument is supporting that position. I found this website that points to all the mistakes made by the states that ratified the amendment, but I don't really plan to research the validity of its claims at this point.

The thought that I do have on the subject and would like to voice is this, How would the other amendments to the constitution hold up to this same scrutiny? It would make a much stronger argument if they could show that it was somehow outside the norm that they behaved in the way they did. Even if they were not acting within the letter of the law, you can't prove conspiracy unless you can show they were acting in a way that was inconsistent with their own past behavior. How many amendments do we have to throw out using this method? How many states do we have to throw out as well? I've heard illegal/unconstitutional arguments thrown around concerning West Virginia and Hawaii, but I'm sure more could be found if you search hard enough.

If it is really illegal/unconstitutional, take a test case to the Supreme Court. If there is sufficient discontent with the federal income tax and sufficient states that don't agree with it, propose a new amendment to repeal it. And no, it does not require Congress to act, there are provision in the Constitution for states to both propose and ratify amendments to the Constitution, it has just never been actually used before (See Article V). There is a legally established process for this, people.

UPDATE: After spending close to an hour looking over the Texas Constitution online, I can find no evidence that it prohibits "the legislatures from empowering the federal government with any additional taxing authority." If it is there, I missed it or it has since been removed through the amendment process (it's no Alabama Constitution, but it has been amended 456 times).

It does, however, require that a bill be read on 3 separate days before voting (as the linked page suggests) but that rule can be suspended, in cases of emergency, by vote of the legislators. I'm not sure why a vote on a Constitutional amendment would be deemed an emergency, but if they held the requisite vote to suspend the rule then that legal argument would be moot.