I agree that areas of human-yeerk cooperation are going to be pretty narrow, and I'm with those who are saying that no realistic scenario justifies involuntary infestation, but you can actually get a lot of the benefits of the schemes outlined here without that nasty involuntary bit. Short of the sorts of ticking time bomb scenarios that are put forward when discussing torture, I don't see that involuntary infestation gets you much that voluntary infestation doesn't.
Take law enforcement. You don't force people to undergo interrogation by yeerk. You offer suspects the opportunity to be interrogated by yeerk. You take three yeerks who don't know each other very well and who have no interest in whether or not the suspect goes free, and you let them each have five minutes with the (willing) suspect. Then you get their stories, confirm that they match up, and talk to the suspect to make sure that the yeerks weren't passing messages through the suspect's memory. If they all say that the suspect is innocent, then s/he almost certainly is. And almost all innocents would be reported as innocent, so it's a nearly perfect test. Pretty soon, juries get used to this, and refusal to undergo investigative Controlling is seen as pretty self-incriminating - like pleading the fifth. The issue in the near-term is that lots of innocent people would refuse because it's creepy, but one expects that people who grow up aware of this sort of option would have less of a problem with it. And juries wouldn't give refusal much weight if they themselves would refuse even if innocent.
As for punishment, I'm with Marie - involuntary yeerking is clearly worse than slavery from the perspective of the person you're doing it to, and we're not willing to make absolute slaves of even the worst criminals. There are perhaps some slight efficiency gains to be made from freeing up space in prisons, and this would use criminals' bodies to benefit society, but in that respect it's no different than taking all of the hardened criminals and making them into delicious meat pies.
But what do the yeerks get out of it? That's easy. There were plenty of willing Controllers in the books, and they were working to enslave the human race, plus they only had something like an hour off every week. Make being a willing Controller slightly less evil and provide reasonable dental benefits and you'd get a whole lot of applicants. It wouldn't be hard at all to find people willing to become occupational Controllers - they'd put in a 40-hour work week same as everyone else, but their work would be providing hosts for yeerks. They could either work for 40 consecutive (waking) hours, or go in 8-hour shifts (or something else entirely, as negotiated by their union). The yeerks are probably just looking to do "human stuff", just as Ax was fascinated with food when he morphed a human, and a lot of people would find going along for the ride while a yeerk uses their body to go skiing to be hugely preferable to sitting behind a counter at the DMV all day. You make sure that those yeerks who are looking to do something dangerous or exotic (mountain climbing, boxing, sex) are matched up with humans who are willing to allow those things, and you have a pretty strict system in place for punishing yeerks who break the rules. Maybe there would be a bit of stigma, but compare this to prostitution.
The yeerks pay for all of this themselves, with the salaries that they earn doing yeerk-specific jobs like the one I described in law enforcement, or doing any of a variety of things that they could do in less problematic bodies - what if one inhabited a shark and gave rides? Can yeerks inhabit unintelligent creatures? Surely some race out there has the technology to give them prostheses to speak and use a keyboard - they could do IT work when not in hosts.
Sure, those yeerks who are just in it for the rush of controlling people against their will lose out, but I'm not going to lose sleep over them. I think it's a mistake to look at this as a difference of perspective (that is, that it's "right for them" to enslave other races). Or, at least, it's a mistake to think that humans have any obligation to respect that sort of difference. Cutting away the complication of Controller-dom, if an alien race showed up which just wanted to kill us all in order to please their gods, it wouldn't be meaningfully unfair to them to do our damnedest to stop them, no matter how important the extermination of all other intelligent life is to their culture. After we kicked their asses, they probably wouldn't find enough voluntary sacrifices to satisfy demand, but we'd still be fully justified in taking steps to make sure that they didn't go find involuntary sacrifices. It simply doesn't matter that it's "part of their nature" to go out and kill other intelligent beings - if we're allowing that as a reason, then we can just as easily say that it's "part of our nature" to react very negatively to natures like theirs.
I have a problem with forcing all yeerks into nothlitism, on the assumption that there actually are yeerks that would be perfectly happy inhabiting voluntary hosts and otherwise contributing to society, but I've no problem forcing all yeerks who abuse their hosts (or who take involuntary hosts) to choose between nothlitism or simple imprisonment.