It's muddy but the Executive isn't making laws it makes regulations constrained by and implementing the laws passed by Congress. It's all nominally rooted in some law the Congress passed and instead of just making those interpretations known when they sue you because you're using a financial instrument to defraud people there's a whole process of making it known how the Executive believe the old laws relate to new situations. Congress has neither the bandwidth nor the knowledge to keep abreast of every novel maneuver around the law so they say this type of thing is illegal and this agency is in charge of saying what type new things are.

A great example of that are with various toxins and pollutants, there's no system in which we can go through the whole process of making a new law every time we discover that some miracle chemical is giving people giga-cancer. Instead Congress tasks an agency full of experts to decide what safe levels of the giga-cancer causing chemical is and makes sure we only ingest slightly below the LD50 of that so we can statistically live.

Yeah, but it's a distinction without a difference because some of the "fill in the blanks" stuff Congress does is so vague that executive agencies in practice write plenty of new laws from scratch. It's not just adding specific items to lists.

And then there's also plenty of cases where the constitution is just ignored without consequence. The CDC unilaterally announced payments to landlords were suspended during COVID, something it had no power to do. It didn't cause much of a fuss.

Regulations are nowhere near that freeform, and they have extensive public review and commentary. The EPA was in court for years debating whether CO2 could be included under the Clean Air Act because they had to stay in the narrow lanes Congress created.

The CDC case seems to make the opposite point: they took a broad interpretation of the public health act, and it was rejected in the courts as exceeding what Congress had intended:

https://www.nytimes.com/2021/05/05/us/politics/eviction-mora...

Right, of course, it was clearly illegal but during the key period the CDC got what it wanted anyway. There were apparently no repercussions for this behavior, is making a decision this latest struck down by the courts are valid justification under federal employment law of the terminating employees?

Clearly illegal? The CDC temporary eviction moratorium went to our conservative Supreme Court and they ruled 5-4 in the CDC's favor. Maybe based on the fact we were dealing with a worldwide pandemic.

Yeah and ultimately in a very real politik way whatever the Supreme Court says is Constitutional is Constitutional because they are vested with the final say on what the Constitution means at any particular moment.

The CDC has pretty vast powers in a public health emergency and IMO the ability to forcibly quarantine people is a power far beyond the ability to pause evictions and is maybe even a necessary part of the former. (Can't really quarantine someone if their landlord can just throw them out right?)

No, they ruled against it. There were two moratoriums. The first was authorized by Congress. When that expired the CDC tried to unilaterally extend it and that was struck down:

https://www.americanbar.org/groups/business_law/resources/bu...

Realtor associations and rental property managers in Alabama and Georgia again sued to enjoin the CDC’s new (“second”) moratorium. The District Court entered judgment for the landlords, and the Supreme Court affirmed.

The Supreme Court found that Congress could speak clearly when authorizing an agency to exercise the powers of vast economic and political significance that the CDC exercised in its order, but Congress had not done so. In addition, the CDC order “intruded” in an area that is the particular domain of state law: the landlord-tenant relationship. Absent clear Congressional authority, which was lacking, the CDC order was too broad and was properly struck down.

Sure, they ruled against the second moratorium, not the first. But it was a close ruling, because it's not as clear as you're making it sound. The CDC has very broad powers during a public health emergency.

Not saying I agree with what Trump's CDC tried to do, but it's not clear to me that the law bars them from taking extreme measures during a pandemic. It just has to be continually justified by facts on the ground.