How do you negotiate with a man who can break his promises at any time?

Historically, however, these compromise agreements were possible because both parties could rely on the other to honor the agreement after it became law. But the Supreme Court’s decision in AIDS Vaccine suggests that, even if congressional Democrats and Republicans reach a deal where Democrats get some of the health care spending that they seek, Trump can simply cancel that spending after the bill ending the shutdown is signed into law. If he could cancel the foreign aid spending Congress authorized, as the Court just indicated he can, why couldn’t he cancel anything else the legislators agree to?