I would never do it on purpose. There have been 2 cases where I have shot a deer in the spine. One was when I was shotgun hunting, a doe stopped at 50 yards from me and I shot her once in the vitals and as she started to run off I hit her in the spine. The other one was when I was bowhunting from the ground and my release broke into pieces when i was 3/4ths the way drawns. In result my arrow flew off early and lobbed into the deers spine. I quickly ran over to it and finished it off with another arrow.

In my opinion a spine shot is a VERY risky shot and I would never aim for it.