Come on, Blender. This is absurd.

In this scene, there is a volumetric spotlight shining on Suzanne which is completely blocked by a plane. Why is it that the spotlight halo is shining right through the plane? How is this supposed to be realistic???

Verified, even changing the normal side of the mesh, or changing the plane to a cube, or putting another Suzann on front makes this still exist… or is this “normal” and “should happen when you’re not using shadow buffers” ?

Set “Halo step” to 1 or greater. See the Blenderwiki page on halo spots for more detail.

“should happen when you’re not using shadow buffers”

Yes it should. Shadows are what stops light from continuing on to other points behind a blocking object. Turn on buffer shadows and do what CD38 said.

Also check Clip end/start and Bias… had something like this problem with my current WIP project. for example set Bias to 0.01 or what ever is the smallest (default is 1)… this might do wonders… or then not.