an assumption of ID you can deduce a testable claim about the world
Deductions and testable claims are only one aspect of things. There are also first principles.
It may be only one aspect, but it is a necessary one. We are discussing (I think) whether ID is a scientific theory and one criterion is that the theory make testable predictions. It is up to those claiming ID is scientific to produce such a prediction. I guess you will join the long line of ID-is-scientific posters to fail the challenge.
And no, contrary to your hyperbole, it is not a matter of law but of convention.
As an aside, it's not clear there are any other necessary criteria for a theory to be scientific.