At the end of the Priority: Citadel mission a stand off forms and Shepard had managed to convince the other Spectre to support him, when the traitor pulled a gun on the Asari Councillor. A red/renegade interrupt opportunity popped up, which I took, and Shepard shoots the traitor.
I was interested to see what could have happened, so I rewound the game to a previous save just to see what the result of missing the interrupt is, and the other Spectre takes the shot instead, with what appears to be the same immediate results.
What I want to know is are there any long term differences depending on whom out of Shepard and the other Spectre takes that shot and kills the traitor?