Great OP Turnbull.

I have often wanted to write such a piece to bring Michael to account for his actions.

Let me first say that you could argue that Michael's eventual descent into mob life could be blamed on either Sonny or Vito

Vito for being too pig-headed to enter into Narcotics with Sollozzo, and Sonny for directly contradicting his father in the meeting giving Sollozzo the impetus to assasinate Vito and get Sonny go into business with him (which was a ludicrous idea knowing how devoted Sonny is to his father)..but these two events set the wheels in motion for ALL that follows.

But if you take it from the point when Mike decides to kill Sollozzo and McCluskey then some great points are raised here, though I do have to defend him on a couple of points

Michael did have to kill Sollozzo, as was said earlier in the film, he was considered a 'civilian' and not a danger to anyone, so Sollozzo had seemingly nothing to fear from Michael meaning he'd come out of hiding and sit down in a public place to meet him. No-one else could achieve that, plus the fact that Sollozzo requested Michael personally, no-one else could have been sent in his place, and had he not gone to this meeting, an insulted Sollozzo may have tried to hit Vito again.

Now whether Mike needed to kill McCluskey is another matter, if Mike just shot Sollozzo and then fled, they could have fed the story that McCluskey was on the take, and presumably, eyewitnesses would testify to McCluskey having dinner with a known criminal and crime-boss' son. That would be enough to see McCluskey done for corruption and a spell behind bars...but one snag, McCluskey broke Mike's jaw...that's the sole reason he killed McCluskey in my view.

I'll come onto some more points later - back to work for me.