A Judge of the law is someone who is supposed to "upon complaint" decide if a law or other legal document is appropriate. They are supposed to remain within the "four corners" of the law (i.e., what is written in the document). External factors not brought up by the plaintiff (the entity filing the complaint) are not supposed to be weighed or used in the decision. Activist Judges are judges who rule not on law, but rather political agendas.
When I was last called up for jury duty (a jury is basically a judge by committee) this story was told to us by the lawyer briefing the jury pool:
There was a lawsuit before the court, concerning damages related to a traffic accident. One of the jurors knew the intersection where the accident had happened. On his way home for the evening, this juror went through that intersection, then stopped his vehicle, got out and took pictures of the intersection. This juror then shared these pictures with the rest of the jury during their deliberations. The judge upon learning about this declared a mistrial because the juror presented evidence that neither the prosecution nor the defense wanted to present to the jury. The jury, because of this one juror going out and discovering facts on his own, had reached a bad (not necessarily wrong) conclusion. Their purpose was to decide based on the evidence presented them, not what they went out fining on their own.
There are also what are known as Plenary Powers in the Constitution. For example, the authority to declare war is a plenary power to Congress. The ability to introduce bills which spend or generate revenue is plenary to the House, while the power to ratify treaties is a plenary power to the Senate. These plenary powers belong entirely to the entity to which they are granted and are not subject to review or approval by another part of the government. The Senate cannot be first to introduce a spending bill, the House cannot ratify a treaty with a foreign government and the President nor the SCOTUS (Supreme Court of the Unites States) can declare war.
So when the 9th Circuit Court of Appeals gets a complaint about President Trumps "Muslim Ban" Executive Order (which I wrote earlier about here) plainly put, no judge has the authority to rule on it because that is a plenary power held by the president as stated in the Constitution, Article 2, Section 3, "...he shall take care that the laws be faithfully executed,...".
Just so everyone has all of the information so you can make your own informed judgement in the matter, here is the Executive Order.
The first paragraph of it reads:
"By the authority vested in me as President by the Constitution and laws of the United States of America, including the Immigration and Nationality Act (INA), 8 U.S.C. 1101 et seq., and section 301 of title 3, United States Code..."
(f) Whenever the President finds that the entry of any aliens or of any class of aliens into the United States would be detrimental to the interests of the United States, he may by proclamation, and for such period as he shall deem necessary, suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrants, or impose on the entry of aliens any restrictions he may deem to be appropriate.
Title 3, Section 301 also clearly states:
The President of the United States is authorized to designate and empower the head of any department or agency in the executive branch, or any official thereof who is required to be appointed by and with the advice and consent of the Senate, to perform without approval, ratification, or other action by the President (1) any function which is vested in the President by law, or (2) any function which such officer is required or authorized by law to perform only with or subject to the approval, ratification, or other action of the President: Provided, That nothing contained herein shall relieve the President of his responsibility in office for the acts of any such head or other official designated by him to perform such functions. Such designation and authorization shall be in writing, shall be published in the Federal Register, shall be subject to such terms, conditions, and limitations as the President may deem advisable, and shall be revocable at any time by the President in whole or in part.
So I have just spent all of this showing you that the president has the duty and authority under the Constitution and the INA to issue that Executive Order.
If you look at the 9th Circuit's ruling which denies the government's attempt to stop the stay, starting on page 13 (section IV. Reviewability of the Executive Order) does the 29 page document begin to address on if the Executive Branch has the power to exercise the EO. I won't quote it because it is five plus pages just on that point. I want to make clear that the law which gives the president this authority was never even brought up, by the government, which is a screwup on their part. If they had made this point and the 9th still ruled this way, that would have violated the "four corners" I spoke about at the beginning of this post.
I am taking note that a major point is the complaint that "there was no public warning on the ban." This is for the sole reason in real life that you never, ever tell bad guys what you're going to do. If you see people parked across the street from you watching your house, you do not walk over to their vehicle and tell them, "It looks like you might be wanting to break into my house. Just so you know, I have an armed security detail starting next week." The bad guys should find out about the armed guard when he rolls up on them.
If Liberals hate the fact that Trump did this, they should change the law, namely abolish section 212(f).