Most people--and most philosophers--think governments have two special moral powers, legitimacy and authority. Legitimacy is what gives governments permission to create and enforce rules through coercion, while authority is what makes it so that we are morally obligated to obey those rules (because they are the rules, and not because of their content per se). Most philosophers also hold that these are in some way separate from justice. That is, they think that at least within a certain range, a government may legitimately enforce what is an unjust rule and that you are obligated to obey some unjust rules. For instance, consider the typical person who thinks, "Well, sure, it's unjust for the government to outlaw pot, but if you get caught, you have to serve your sentence."
(You can skip this part to get to the meat of the post)
Usually philosophers say that what makes otherwise unjust acts legitimate and/or authoritative is that they result from the right kind of political process, a process which somehow confers these two moral statuses to what would otherwise be an unjust action. For instance, David Estlund argues that an unjust order or law can be legitimate and authoritative if meets the following four conditions:
1. The act one is ordered to do is a token of a type of act that could in principle be justified.
2. The decision process used is one that is publically justifiable to all reasonable people.
3. The order results from reliable and fair decision process—a process that usually tracks the truth as well as any other process that meets condition 2.
4. Those who issue the order sincerely and in good faith believe that the order is justified.
Note that condition 1 here does not rule out unjust actions. In principle, we can think of situations in which it would be permissible for me to kill you. So, for Estlund, if the other 3 conditions are met, then I may be both licensed and obligated to kill you when my commanding officers orders me to do so.
In When All Else Fails and some other papers, I explain why I don't find Estlund's main argument convincing, and I won't repeat all the details here. The main issue is that Estlund relies on casuistical reasoning to motivate intuitions on behalf of his view. I don't share his intuitions. As a public reason liberal, he has to overcome and defeat my reasonable objections, while--since I am objecting to coercion rather than defending it--I don't have to overcome or defeat his. He hasn't, so the argument doesn't succeed. Further, it's far from clear that, say, democratic decision-making in real-life is a reliable for fair process. Even if it's as reliable or fair as any other process that meets condition 2, it's not clear why that's good enough, since it's still very unreliable and quite unfair.
Instead, I want to explore a broader issue with all views that say, "It's okay to do unjust things as long as you decide to do them the right way."
Consider three killers. Ann takes bath salts, goes crazy, and murders someone on the street. Barbara catches her lover cheating on her, and kills her in a fit of rage. Charlize reads certain kinds of anti-moral realist philosophy and concludes that morality is just a way of talking to push people around. She becomes a moral nihilist and moral skeptic because she finds their arguments convincing and she's convinced morality is just bunk. She decides it's thus not really wrong to kill her neighbor, so, for the hell of it (not out of spite or anger), she pays a hitman to kill him.
If these three people were caught, we'd normally judge Charlize as worse than the other two. She'd be charged with first-degree murder, while the others would get lesser charges.
So, here's the issue. Philosophers often say that it's okay for governments to violate people's rights, or for voters to vote to do unjust things, so long as they do it the right way. If we deliberate and then violate people's rights, that can be (within certain limits) legitimate and authoritative. But politicians just decide spur of the moment to do it, it's not.
Why not hold that deliberation which leads to rights violations instead is especially heinous and evil? Instead of saying "It's legitimate to X because we did it after deliberating" why not say "Wow, you deliberated and then decided to violate my rights? That's even more evil that had you done it on impulse."
A: "Hey, you guys are throwing me in jail for smoking a plant that makes me happy.If you read the empirical literature on marijuana, you'll see there's little or no public justification for doing so."
B: "Yeah, but we spent like six months debating this and then decided to do it."
A: :"Oh, wow, you're especially rotten, vile people. It'd be one thing if you just panicked and did this. But you spent months deliberating and then decided to violate my rights? Given that you spend that much time thinking about it, you should have realized it was the wrong thing to do."
If anything, though, this dialogue understates the problem, because the "deliberation" or "debating" in question for most laws is not well-reasoned, well-argued argument based on evidence, but demagoguery and idiocy. For instance, the actual process that lead to marijuana being criminalized was racist moral panic, not well-reasoned, evidenced based debate that unfortunately got the wrong answer.