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.
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.