Did the comics explore how the Turtles developed their code of conduct?
 

Like how they decided to be crime fighters and how they would go about it?

Are there certain things the Turtles wouldn't do in certain situations?

The Turtles aren't and were never crime fighters in the comics.

It really depends on which iteration you're asking about. In the Mirage comics they discuss the ethics of their ninja code quite often, especially during the City at War arc, while in the Archie comics it's not often touched on.

It's inconsistent how they feel about killing and fighting crime in mirage. One second they're stabbing mobsters for no reason and the next Dons freaking out cause he shot a few people.

Yeah, for a great example of that there's the Cha Ocho origin issue of Tales of the TMNT (Vol. 2).

Cha kills the guy who murdered his wife. Leo tells him that vengeance is wrong. Cha reminds Leo that he killed the Shredder to avenge Hamato Yoshi. Leo scars Cha's face so he'll think about what he's done.

Perfect logic!

Anyone remember the issue with the "toitlenlenator"? who's life they ruin so he goes insane and splinter convinces him he's a turtle and he kills himself.

I wouldn't count that one since it's a one-shot written by a guest artist.

That doesn't change the fact that its the best issue ever!

It's somewhat relevant that in Mirage, Leonardo eventually gives up killing people and starts using a blade that knocks people out instead.

After like, 100 years of killing people, but yeah.

Dude, it's post-"City at War." Leo even tells Cha (and I just pulled out the issue to make sure I wasn't making this up) that he's learned the errors of seeking vengeance.

I'm actually surprised you of all people read it that way. To me, it's one of the best bits of character continuity in the Mirage series.

Anyway, to be honest, I don't think the Mirage universe is all that inconsistent with the Turtles' killing policy in general. It varies depending on the author (especially during the loose canon of the Volume 1), and the opening, Miller-style issues are bit freer with it because of the tongue-in-cheek aspect, but overall it follows a fairly steady path of "okay with killing when necessary, less okay with it as they age, and less okay with vengeance specifically after 'City at War'."

I don't think Laird/Eastman/Lawson wanted us to believe Don suddenly developed a pacifist complex. All the Turtles knew they had very clearly accepted a mission to kill the Elite. I always took it as Don being uncomfortable with the gun, with how brutal and different is from taking a life in hand-to-hand. The issue really lingers on the weapon. The event may have caused him to question their choices more generally, but it really seems the inciting incident was the gun, not the violence.

It's after he kills Complete Carnage, specifically.

I was about to say that if there were any motivation beyond, "Wah, my girlfriend died and now that I've avenged her, I'm done," it was pretty weakly implied, but then I remembered he actually came to forgive Carnage at first (again consistent with his post-"C@W" characterization). So it all works out pretty well. It seems like the decision to stop killing would have come sometime before that, in the years coming to terms with Radical's death.

Last response. I wouldn't say this is exactly true.

While they aren't crime-fighters in the same vein as, say, Batman, or even the 1987 cartoon version of the Turtles, it isn't as if they never lift a finger to help. Most of the craziness they get mixed up in come to them, but they do intervene in muggings they find while out in the city, and I believe on a few occasions they purposefully investigate crimes.

It's just that those incidents are rare and it isn't something they really concern themselves with.

They weren't crime fighters in the cartoon either. They were just after Shredder and Krang because most of everything Shredder thing involved them anyway. Any other time, they just casually run into trouble. So even in the 80's show the Turtles were not patrolling the streets for crime to fight.

Well sorta. I mean what Leo killed wasn't really Shredder. He was a clone. The real Shredder technically killed himself. Though I think Leo was being a massive dick in that issue I think his point to Cha was "Don't make the same mistake as me." Cause I mean what happened when Shredder was killed? City At War.

I basically agree with your assessment here but I must add that I don't think you could so quickly discredit the violent aspect of killing with a gun and how that would affect Donatello, specifically. I always took it as he was appalled at both the gun and its usage, how quickly and violently it claimed life with little to no skill required.