[cyberax]

> Each state would have to work within the constraints of its state level constitution for levying that tax.

Interstate compacts exist. For example, states can make an agreement that a company can receive grant funds only if it's incorporated in a state that spends a certain percentage of the budget on scientific research.

San-Francisco (in a ham-fisted way) tried to do something similar, by prohibiting city-sponsored contracts with companies in states that restrict abortion.

[dragonwriter]

> Interstate compacts exist.

Not without positive action by Congress they don't. (US Constitution, Art. I, Sec. 10.)

[cyberax]

As I replied in another message:

That's not quite correct. The judicial practice in the US is that the intestate compacts (agreements) require Congressional authorization only if they infringe on the sovereign Federal powers.

One good example for the 2nd Amendment lovers: states are free to make reciprocal agreements with other states for concealed carry permits. It doesn't require any authorization from the Congress.

Another example are the laws for taxation of multi-state corporations that the neighboring states can negotiate together.