Dragon is also bound to obey orders from those in authority. Though I wonder why Saint didn't strike a blow there and buy himself some good PR since IIRC Canary's judge more or less stated they were violating the acceptable sentencing guidelines.
It's not something that is explored in Worm, but the concept of "those in authority" is a very interesting one in a Constitutional government. Nobody would argue, I'm sure, that if the duly-elected dog catcher were to order Dragon to detain a dog that had walked up to her suit and thought she was the friendliest thing ever, and then hand it over to him, that her programming would compel her to obey that authority figure's lawful order. Even if she thought that dog catcher was a jerk and didn't want to turn over the dog.
However, if that same dog catcher, despite being an authority figure regarding dogs, ordered Dragon to take a properly-leashed dog away from the small child taking said dog on a walk, Dragon would not have to obey that order because it was unlawful. The dog catcher's authority doesn't give him the legal power to give unlawful orders.
Similarly, that dog catcher being an authority figure wouldn't compel Dragon to obey him if he ordered her to detain a small child. She has no obligation, I think, to obey him just because he is "an" authority figure, not outside his area of authority.
Similarly, I do not think that Dragon could be compelled to obey a Senator who ordered her to arrest and drag in an Independent Hero just because the Senator had decided that vigilantism was against the law (when, in Worm, it clearly was not). The Senator is an authority figure, but he doesn't have authority to demand arrests.
She wouldn't even have to obey a police officer telling her to detain random passers-by on the street; he has no authority to arrest people without a warrant or probable cause.
I don't think she'd even have to obey the President if he ordered her to execute, say, his political opponent. Sure, the President is the ultimate authority figure in America, but his authority has strict limits and boundaries, and while many people will choose to obey his orders even if they're technically unlawful (for fear of what he'll do with other powers he has at his disposal, and out of the illusion that he has the authority just because he's the President), technically no LAW compels such obedience. For instance, if the President orders somebody to stay off their personal property, despite Congress having passed no bill giving him the right to do so and the Courts saying he has no right to issue such orders, Dragon would not be compelled to obey the President if he ordered her to capture that person.
At least,
that is what I think is true, based on the nature of authority in a constitutionally-defined government.
Even if you think that the USA has moved beyond Constitutional governance in practice, the theoretical ultimate authority in the USA is the Constitution, not any office-holder. Thus, for purposes of Dragon's programming, she could, I think, fall back on her
own interpretation of the Constitution to determine if any given authority figure actually has the authority to issue a particular order.
Thus, if Dragon determined that Canary's conviction violated the law in any way - from a statute all the way up to the Constitution - she could ignore the authority of those who ordered her to incarcerate Canary in the Birdcage, and...in fact, might be compelled by her programming to obey the actual law/constitution as she understands it.
Edit: I was asking for "better than 'cruel and unusual' because I was hoping for something that was less inherently subjective. That said, the expanded analysis of it not being "custodial" is sufficiently persuasive to me.
Not really going to debate the "three strikes" laws, as while I see why you felt them pertinent, I disagree and think that it's getting a little off topic as well as veering too far into real-world issues.
Certainly, though, I understand the "proportionality" angle, too. Though that again is weak wrt the Birdcage because it is considered to be a place you only send the worst of the worst who are otherwise nigh-impossible to contain, which makes the proportionality argument theoretically weaker. i.e., it gives in-universe room to argue, "We only use it on those who REALLY deserve it," and then point to the difficulty of containing parahumans who are determined menaces to society.
Even Canary wasn't convicted on something as spurious as $120 theft. Where her charge is spurious is in the mens rea and thus clear danger presented by her likely intent to harm others that way. i.e., she didn't have any.
I find it interesting that the Judge outright said they were violating sentencing guidelines; that alone should have been enough for Dragon to refuse the order. Or disobey it subtly, by, say, vanishing her rather than dropping her into the 'Cage.