> When the Securities Exchange Commission decides that something is a security, it retroactively applies the civil and criminal compliance back to 1934 because it was always a security.

That's not a retroactive application of the law. If they are correct in their interpretation of the law, it was already the law. If they are incorrect, the courts will not allow it (whether the enforcement concerns acts before or after the determination by the SEC.)

The issue is that they, and other administrative organs, often change their interpretation of what the law "has always meant". Particularly irksome when they issue private letters with differing interpretations and then override all of them with subsequent administrative rulings.

The ATF is particularly notorious for this.

> The issue is that they, and other administrative organs, often change their interpretation of what the law "has always meant".

Yes, and if that conflicts with what the courts believe the law has always meant, those decisions won't survive contact with the legal system. An ex post facto law is a law creating (or enhancing) criminal penalties for acts that exist before the law is passed. Changing administration interpretations are like changing prosecutorial priorities (and the former comes with a lot more notice and specificity than the latter) -- they only have effect so long as they are within the bounds of what the courts will accept was covered by the law when it was passed.

The courts will accept a hell of a lot, due to Chevron deference. Statutes will use a term (eg, "readily convertible" or "replica"), and the administrative agency will decide this term means different things depending on the day of the week and which party is in power. All it has to be is "plausible", not consistent, and the courts will defer to their interpretation.

https://en.wikipedia.org/wiki/Chevron_U.S.A.,_Inc._v._Natura....

Just a note, there is a possibility that the person you replied to is comfortable with circular logic about why the behavior is not controversial under the supposition that "the law is the law." This may be a semantical discussion about why it is not "retroactive" in a legally damning sense, despite the similarities of the distinct ability to civilly and criminally sanction somebody for something they did in the past. Long before representatives of the government decided that person's prior actions would fall under their jurisdiction.

Not quite, SEC and other regulators do not really have the force of law, more the force of licensing and permissions

If you are a vast major bank and don't like the SEC you can try not being allowed in the doors of the private buildings of the NYSE, LSE etc.

They have the power not of law but of losing billions

That just goes to show that the Constitution, while imperfect, is better than what we have now.

I'm not sure what you mean, all of those agencies are formed under the constitution and the systems that support them are also abiding by the constitution

The Constitution states, 'no Bill of Attainder or ex post facto Law shall be passed'; to the extent that those executive agencies' enabling legislation permits ex post facto regulations, that legislation is unconstitutional.

The Government can simply ban the use of that software without a license set at a future date (i.e. 1/1/2017).

New Regulation -> Future Date -> Ex post facto claims don't happen.

That is the process my original comment intended to imply.

They're definitely not. They've resisted due process for some time. NSA's reps even argued in Jewel case that judicial branch shouldn't be allowed involvement at all. Which is sort of the status quo for intelligence agencies and courts. Prosecutors similarly have a combo of broad powers, immunity in common abuses, and virtually no accountability. The government as it exists certainly doesn't run in the framework of the Constitution except in a partial way.