The Acting Director of National Intelligence should not be permitted to defy a subpoena...

[FBaggins]

22. The signing statement itself has little effect

It's just a statement of how the executive branch intends to interpret the law (which is their job). What matters is whether or not the part they object to actually is unconstitutional... and it only becomes a factor if and when two things happen:

1 - The executive fails to follow that part of the law, and
2 - The legislature takes them to court over it.

As an example - Congress frequently puts in some notification requirement to a new act. "You can have this money, but you have to send the deputy undersecretary for basketweaving up to the Hill twice a year to report how it's going or the money goes away". That's an unconstitutional arrogation of executive authority to the legislative branch... but is it worth vetoing an otherwise acceptable bill? Nah.

So the President signs it... but includes a statement that translates to "Keeping y'all informed sounds like a good idea... so we'll try our best. But we're stating right here that you don't have the Constitutional authority to require us to do that... so if we can't... we won't. No offense intended" So long as everyone plays nice... it isn't an issue. But if the President doesn't do it one year and the Congress decides to sue over it... they're going to lose. I can't remember any case like this that they've won. So it doesn't go to court. Both sides bluster and show their tailfeathers and they cut some sort of deal to save face.

At this point, signing statements = ' the next guy here can be required to obey; I just ain't gonna and congress can fuck off.'.

Actually... I think it's just the opposite. "It seems reasonable to me so I'll do it. I just won't tie the next President's hands"