I was thinking about internal torques and why they cancel, and I can't figure out how torques from magnetic forces cancel. Say you have two point charges moving with nonparallel velocities. The magnetic forces they exert on each other are opposite and equal, but they aren't along the line between the two charges, so their torques don't cancel in general. This is worrying to me because it means that their angular momentum could change without an external force, which seems wrong. Could someone please show me where I'm going wrong?