(CNN) The enforcement of President Donald Trump's executive order halting the admission of refugees to the United States came to a grinding halt this weekend after a federal judge in Washington state issued a temporary restraining order. The judge's ruling, which the President soon condemned on Twitter, raises more questions than it answers.

The state of Washington argued before Judge James Robart that the restraining order should be issued to stop any harm while it pursues its case. The state's lawyers argued that it is likely to ultimately prevail in this case because the executive order violates the Constitution and federal law.

Among the offended legal principles, they contend, are the Equal Protection Clause; the Establishment Clause; Due Process; and the Immigration and Nationality Act (INA). It offered detailed reasons why each of these were violated by the administration's order, which blocks citizens of seven Muslim-majority countries from coming to the United States for 90 days, prohibits all refugees for 120 days and places an indefinite halt to admission of refugees from Syria.

The plaintiffs sought a preliminary injunction, as well as a temporary restraining order. The TRO was granted Friday; the preliminary injunction has not yet been decided.

An injunction is a court order commanding a person either to perform or to refrain from performing a particular action.

In this case, the district court has not yet decided on the request for a preliminary injunction. And even a preliminary injunction is not a decision on the merits. A preliminary injunction only preserves the status quo pending a resolution on the merits.

So, what's the difference between a temporary restraining order and a preliminary injunction, if the preliminary injunction itself is "temporary"? The preliminary injunction preserves the status quo and the rights of the parties until a final judgment on the merits, while a TRO preserves the status quo before a preliminary injunction hearing may be held, because even that date isn't soon enough.

Photos: Yazidi toddler waits without his parents for surgery Photos: Yazidi toddler waits without his parents for surgery Dilbireen Muhsin, a 2-year-old boy from Iraq's Yazidi community, was born in a refugee camp January 4, 2015. Hide Caption 1 of 12 Photos: Yazidi toddler waits without his parents for surgery Dilbireen, a cheerful child, has a love of animals. Hide Caption 2 of 12 Photos: Yazidi toddler waits without his parents for surgery Around his first birthday, Dilbireen was burned in a fire. He flew to the US for reconstructive surgery on his face in October. Hide Caption 3 of 12 Photos: Yazidi toddler waits without his parents for surgery Since his first surgery, Dilbireen has been cared for by a Yazidi advocate, Adlay Kejjan, in Michigan. Hide Caption 4 of 12 Photos: Yazidi toddler waits without his parents for surgery As Dilbireen waits for his second round of surgeries, his parents, who are still in Iraq, have finally been issued visas so they can come to the US to be with their son. Hide Caption 5 of 12 Photos: Yazidi toddler waits without his parents for surgery Dilbireen celebrated his 2nd birthday in the US last month. In a message to the boy, father Ajeel Muhsin said, "I am hopeful that we will come soon. Finish all your operations. After that, we will return to Iraq. We love you. Kisses." Hide Caption 6 of 12 Photos: Yazidi toddler waits without his parents for surgery Dilbireen has grown into an independent toddler who brushes his own teeth. Hide Caption 7 of 12 Photos: Yazidi toddler waits without his parents for surgery Kejjan said said she prayed that Dilbireen's parents would get the travel visas they needed to by their son's side. Hide Caption 8 of 12 Photos: Yazidi toddler waits without his parents for surgery Dilbireen has started to notice that "he is different," Kejjan said. Hide Caption 9 of 12 Photos: Yazidi toddler waits without his parents for surgery "When he plays with kids, he like touches their eyes and nose. He realizes there's something different about him, and it's really, really sad, because these kids, they run away. ... They're always scared of him," Kejjan said. Hide Caption 10 of 12 Photos: Yazidi toddler waits without his parents for surgery Kejjan, who works as a pilot, has shown a curious Dilbireen how airplanes are operated. Hide Caption 11 of 12 Photos: Yazidi toddler waits without his parents for surgery Kejjan, who also works as a paramedic, has shown Dilbireen some of her medical equipment. Hide Caption 12 of 12

The difference really boils down to the level of exigency. A preliminary injunction is time-sensitive, even urgent. A TRO is an EMERGENCY.

That's why a temporary restraining order and a preliminary injunction share the same high standard . They are both considered extraordinary remedies, never awarded lightly , or as a right. They should not be granted unless the plaintiff clearly shows it is entitled to one.

The state of Washington, as a plaintiff, had to establish it was likely to succeed on the merits, likely to suffer irreparable harm, and that this injunction would be in the public interest. Serious questions going to the merits can also support issuance of a preliminary injunction, too.

The Trump administration and the Department of Justice argued that the state was likely to fail when a judge ultimately rules on the merits of the case. According to the DOJ, Congress has complete power over the admission and exclusion of aliens, which it has expressly delegated to the President through the INA.

A provision of the Immigration and Nationality Act titled "Suspension of entry or imposition of restrictions by President," 8 U.S.C. § 1182(f), authorizes the President to "suspend the entry of ... any class of aliens" whenever the President determines their entry "would be detrimental to the interests of the United States."

Both sides had well-reasoned arguments, based on federal law or the Constitution itself. So, which argument was most persuasive?

The court's heavily-anticipated written opinion prompts all sorts of questions. There's no indication which legal argument actually won over this judge. Was it one of the constitutional claims, like Equal Protection? Or was it the argument that the executive order violates federal law, like the INA? For the most part, we're left wondering.

The opinion discusses in some depth the standard for granting injunctive relief. But that's neither controversial nor newsworthy; the standard itself is well-established law. The court then simply concludes that the plaintiff has met its burden -- without really telling us WHY.

In fairness, this opinion was issued at breakneck speed. Plus, this kind of determination is not supposed to be a decision on the merits. It's actually the opposite: It's a temporary fix -- until the court can have another hearing, to decide whether to apply another temporary fix (preliminary injunction); until eventually the court can someday have the hearing that actually decides the case on the merits.

When you look at it in context, the judge had a good reason not to get too deep into the merits of the case in this TRO. That good reason is: A TRO is not supposed to be a determination of the merits.

The Trump administration has said it will file an emergency motion to set aside the judge's restraining order. And Trump has tweeted that the opinion from a "so-called judge" is "ridiculous." How will the appellate court analyze the judge's decision if there isn't much to go on?

The 9th Circuit Court of Appeals reviews a district court's preliminary injunction for abuse of discretion, a limited and deferential standard.

That standard means that if the District Court identified and applied the correct legal rule, the appeals court will reverse only if the court's factual findings were illogical, implausible or without support based on the facts in the record.

So on the one hand, the appeals court as a rule defers to the lower court. On the other hand, where the written opinion is sparse on identifying legal rules or factual findings, the 9th Circuit might not have much to defer to.

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As an even greater challenge to the Trump administration, a temporary restraining order is not classified as an injunction. It is not generally subject to appeal as a right , though under these extraordinary circumstances, there's no telling how the appeals court might handle it.

As an alternative to appeal in the 9th Circuit, the Trump administration could try to file a motion with the same District Court, asking it to stay its TRO. Essentially, the defendant could ask the court that issued the restraining order for a restraining order -- of the restraining order.

Ultimately, one way or another, this case ends up at the Supreme Court. Other cases are pending throughout the country, and the odds are that there will be a serious split among the federal appellate courts, one that can only be resolved by the high court.

That same court, of course, is currently composed of eight members and capable of a 4-4 split. That's where it gets strange. When cases tie at the Supreme Court, then the appellate court's decision stands.

In this case, that could take the country right back to where it started, which by then might be legal chaos.