In Politico, Josh Gerstein writes:

Some attorneys believe the Justice Department is intentionally dragging its feet in the Hawaii case because the 9th Circuit rotates the three-judge panels assigned to motions every month, with the next swap-out due Saturday. The 9th Circuit also announces the panels publicly, although not in advance. This month’s consists of two Obama-appointed judges — Morgan Christen and John Owens — along with George W. Bush appointee Milan Smith.

There is another possible, procedural reason.

The district court in Hawaii issued a Temporary Restraining Order (TRO). Currently the parties are litigating how to convert the TRO into a Preliminary Injunction (PI). As a general rule, TROs cannot be appealed–appellate review is extremely narrow. For reasons I explained here, the 9th Circuit in Washington v. Trump ignored that rule. In any event, it is not in the government’s interest to appeal a TRO, as–traditionally at least–it bears a much higher burden than if it is appealing a PI. (There is a reason the Obama Administration did not seek a stay from the Supreme Court when the 5th Circuit denied a stay in the challenge to DAPA). Further, the District Court in Hawaii issued a very broad injunction, that even enjoined internal-looking aspects of the order, such as instructions to the Secretary of State to research other countries to add to the vetting list. The government has asked the court to narrow its scope. There is every reason to solidify the scope of the preliminary injunction before going up to the 9th Circuit. Indeed, if this is the case that goes up to the Supreme Court, I would much rather go up on a PI than a TRO.

In contrast, the federal district court in Maryland (almost certainly) issued a preliminary injunction. I hedge a bit because the court was cagey about the precise relief it was entering. However, the analysis itself suggests that the PI framework was being applied.

For example, on page 18, the court states:

To obtain a preliminary injunction, moving parties must establish that (1) they are likely to succeed on the merits, (2) they are likely to suffer irreparable harm in the absence of preliminary relief, (3) the balance of equities tips in their favor, and (4) an injunction is in the public interest.

On page 39:

While Plaintiffs would likely face irreparable harm in the absence of an injunction, Defendants are not directly harmed by a preliminary injunction preventing them from enforcing an Executive Order likely to be found unconstitutional.

The government’s brief treats the opinion as a preliminary injunction, which I think is right.

Here, the government has promptly appealed the preliminary injunction, but has not appealed the TRO–the scope of which may be narrowed when it is converted to a PI.

As a result, when faced with a choice of appealing the temporary restraining order in Hawaii, which the government is trying to convert to a narrow preliminary injunction, or appeal a narrow preliminary injunction in IRAP, the prudent choice would be to focus on the latter.

I have no inside knowledge, and this is a non-cynical reason to explain the different litigation postures.