Disabling collision between two perticular bodies

The collision between two bodies be detected but the physics bounce is what i want to avoid. Is there a way that I can disable the collision and let a particular object pass right through the collider and also allow collision between another object.
In any script , to preferred JavaScript.
example:
ball 1 ball2 wall;
ball1 pass thru wall but ball2 collides with wall .
reply,
Do3D

A couple of options would be to use collision layers, or use the physics ‘ignore collisions’ function (search the docs for more info).