The very short form of the interference rule is that you can't make contact of the ball, unless another player is actively blocking you (by moving, stationary doesn't count). At that point you can then initiate contact with them off the ball.
That applies to defence and offence.
@H-Bomb started
London Fixed Gear and Single-Speed is a community of fixed gear and single-speed cyclists.
The very short form of the interference rule is that you can't make contact of the ball, unless another player is actively blocking you (by moving, stationary doesn't count). At that point you can then initiate contact with them off the ball.
That applies to defence and offence.