The Supreme Court ruled on the constitutionality of executive agreements in 1937.
A little bit of history on executive agreements like this:
Prior to 1940 the U.S. Senate had ratified 800 treaties and presidents had made 1,200 executive agreements; from 1940 to 1989, during World War II and the Cold War, presidents signed nearly 800 treaties but negotiated more than 13,000 executive agreements.
Everyone needs to just calm the heck down about all this. You are being spun by Trumps minions.
The Supreme Court has made a lot of unconstitutional rulings but that doesn’t make the rulings correct.
The Supremes ruled that a sawed off shotgun was not a militia weapon, despite the fact that the army used them as "trench guns". The Supremes ruled that homobamacare was Constitutional as a "tax".
You can either be a Conservative, or you can keep saying the things you do to excuse the shredding of our Constitution.