So I'm up through episode 8 of Season 3.
I don't recall what was discussed before, but basically after this episode and the prior, we see a more cynical Jimmy -- it's clear that desperation (due to needing money), boredom (because he can't practice law for a year), and frustration (at those who take advantage of him or abuse him in some way) coupled with opportunity is increasing the speed of his moral drift. Having to destroy his brother in court to keep from being disbarred has led him to more embrace the darker side.
I think that his refusal to help Chuck at Rebecca's request after the trial is reasonable. (Her request is really unreasonable despite well-meaning, based on the context of what has gone on between Jimmy and Chuck.... Jimmy was the abused, and you would not ask the abused to "get over things" and keep helping their abuser especially after they've finally just managed to get out from under their thumb... maybe after a long time has passed, they could reach that point? But not immediately... and especially not when part of the abuse was Jimmy constantly helping Chuck while Chuck loathed him and took advantage of his generosity. Rebecca was unfair here).
But where Jimmy really takes his dark turn is when he can't get his malpractice insurance premiums reimbursed, so out of what amounts to petty spite he decides consciously to screw over Chuck by offering a sob story with the sole purpose of conveying "accidentally" that Chuck is mentally ill. As it is, Chuck has actually been doing something admirable -- realizing that, however horrible it was, Jimmy's argument during trial was convincing and he has a mental (rather than physical illness), he embraces this new hard truth and decides to get better. He's still rather lousy at pacing himself and relying on others on difficult tasks, but you can admire his embrace of truth and his tenacity to survive and thrive. (It's actually the first time I have been able to identify with Chuck. It's easy to criticize him for being unrealistic about the difficulty of overcoming mental illness; at the same time, I remember pushing myself very hard in situations where I felt I needed to overcome something. For example, when I had invasive surgery, I remember pushing myself to go out as soon as I could and become active again, so I ended up being weeks ahead of the typical healing timeframe others experiences... I would return after my outings a bit dizzy, weak, and exhausted, but I was independent much sooner than expected. Because it was a "mental" thing for me, my mind asserting itself over my condition. And I can admire Chuck's perseverance and drive to regain mastery over his existence without making excuses or allowances. Once Jimmy "proved" to him that it was a mental condition, Chuck did not shirk from accepting that truth; he embraced it and then tried to deal with it.)
Anyway, this is one of the first major "evil" things Jimmy has done that can't be justified per se somehow, and if I recall correctly, it basically undermines Chuck's endurance and ability to persevere through a fragile time... contributing to the dark finale of Season 3. He's got blood on his hands in some way or form from this.
Also, he is embracing the "slippin' Jimmy" persona willingly... once literally (when he blackmails the music store owners) and twice morally (that, and bullying the work hour overseer who was distasteful). It's all small stuff in some ways (whereas Mike is usually involved in life-or-death plotlines), but you can just see the connections light up in Jimmy's eyes -- like Walt's confession, he likes it, he's good at it, and it makes him feel alive. And damn, is it but lucrative ... easy money, just for running his mouth and/or carrying out a scheme.
Another thing I appreciate about the show is the complex moral tapestry of its protagonists. Nacho, for example. Yeah, he's morally compromised, being in the drug trade, but you can tell that while he has to put up a tough fearsome front, he has a heart. He loves his dad and wants him to stay out of the trade, to the degree he's willing to take drastic measures to protect his dad. He also wants to be sympathetic to Crazy 8, yet he's forced to (by the others around him) to take severe steps to keep everyone in line. He's like a guy who wakes up sometimes and wonders how the hell he got to be in his position because he finds it distasteful on some level, and doesn't necessarily like dealing with all the maniacs and ruthlessness, yet he also willingly went there and isn't just extracting himself. Basically he's still got passions and shreds of conscience left, and it makes his road harder than Tuco's or Hector's.
Finally, a lot of discussion probably focuses on legal vs illegal, good vs evil... but I don't recall if we've discussed professional versus unprofessional/expedient. There's so much discussion of what it means to be a 'respectable' lawyer -- or at least present the veneer of being such -- versus one who doesn't cross t's and dot the i's, one who cuts corners, and maybe undermines the fabric of the law. How does one have integrity? Well, along with maintaining certain standards (and some of the characters do maintain those standards like Kim, while others don't, and still others work to fabricate the APPEARANCE of such while kind of sliding a bit because appearance and reputation matters like Chuck and Howard), there's also a sense of maintaining one's honor [among thieves?].
So along with the legal explorations, we see the criminal side and who is reputable versus not. Mike is a professional -- he says what he does and does what he says, and he doesn't take money for things he does for himself or when he's agreed to not take money. His word is his bond. Whereas Jimmy is all words (he does his "Jedi mind shit" with his slew of neverending speech), Mike believes that actions speak in lieu of words and his speech economy is severe. The same kind of code goes for Gus Fring (who is also an interesting study in complex moral dynamics -- he's a guy who is making tons of money off selling drugs to junkies, yet he's also very admirable, forthright, a community icon, that speech he gives to his crew at Pollos Hermanos is inspiring and pretty authentic aside from the overall duplicity of it, and so on.). This is contrasted with the backstabbers, the crazies, the incompetent (e.g., the guy with the baseball cards), and those without anything they believe in aside from rampant greed and cruelty.
Anyway, that's another huge element of the show -- the professional / honorable who do their work with high standards (Kim, Mike, Gus), versus those who don't take pride in their work or live by any kind of ideal AKA the amateur, the hack, the lazy, the self-absorbed.
I'm still trying to map the Francesca we see in Season 3 (who seems to be a well-measured, pleasant, optimistic, considerate person) with the frustrated and rude woman we saw in Breaking Bad. There's another "slip" waiting to happen...
It's actually kind of sad watching all this, for poor Mike, knowing how things work out for him. He's an impeccable professional who loves his granddaughter and always has tried to compose himself in the best possible way to what he did on the police force, he's scans as a man who knows he is damned but is going to be as true to his word as he can, who unfortunately had to intersect paths with the likes of Walter White. Walter really destroyed a lot of lives and was so self-absorbed he really failed to grasp how awful he was in the process.