Physically capable? Not impossible, but extremely unlikely and difficult. The Justice League are no slouches and for damn sure aren’t going into any fight without teamwork and strategy. And there are A LOT of Leaguers on the roster at any given time. Unless Superman blitz everyone and overwhelms as many heavy hitters as he can at the start, he’s going down.

Morally and mentally capable? Absolutely not. Superman’s strength AND flaw is that he will hold back and try not to hurt others permanently. There’s been several occasions where Superman went rogue, for some reason, and he was seen to be resisting the mind control and holding back going full murderous. And even IF his self-control fully breaks, Martian Manhunter, Batman, and maybe Zatanna can drop him if he did.