Justice becomes personal the moment your own side violates the principle.

It is easy to hold a principle when it costs your opponents. The moment it would cost your own side, the exceptions begin: this case is different, the stakes are higher, they started it. Whether you actually believe in the principle is decided entirely there, and nowhere else. Everyone applies their standards to their enemies without effort.

Watch for the moment your own group does the thing you condemned. Say something, even mildly, even privately. The cost is real and usually smaller than it feels, and the alternative is discovering that what you took for conviction was only allegiance.