Um, It's Called A SYSTEM OF CHECKS AND BALANCES

From Trump's twitter feed:

What is our country coming to when a judge can halt a Homeland Security travel ban and anyone, even with bad intentions, can come into U.S.?

— Donald J. Trump (@realDonaldTrump) February 4, 2017

Donald, it's part of a system we like to call (and perhaps that should have been posited in the past tense) a system of checks and balances.  You see there are THREE (not just one!) branches of Government as defined by The Constitution.  You're sitting at the top of JUST ONE of them - the Executive Branch.  Then there's the GOP-controlled Congress (made up of two bodies, the House and the Senate) - that's the Legislative Branch.  They make the laws and you implement them.

Since you seemingly have bullied them into submission, it might LOOK to you like you control everything.  But you don't.  Not everything.

It's THE THIRD branch, The Judiciary, that decides if the actions of the first to are in agreement with The Constitution (remember the Constitution?  I guess you haven't read it since Khizr Khan offered you his copy, Sad!).  If an action is in agreement with the Constitution, then fine.  It continues.  If it doesn't, then it can't continue.  That's how this halt on your immigration ban came to be.

It's a function of the system of checks and balances of the three equal branches.  Did you know that, Donald?  Did you know that there are three equal branches of constitutional authority?  Hasn't anyone ever told you that?  Were you listening when they did or were you thinking of grabbing some pussies and you missed it.

In a constitutional democracy/republic every one has to play by the constitutional rules, Donald.  Even you.

It's frightening to me that you need to be reminded of this.