This is what taking sides looks like. The right side was taken completely off, leaving only the left. The view from the other side would show that the left side was taken completely off, leaving only the right. It is not such a good picture because it is difficult to distinguish the extent of the damage from what is going on in the background. Realistically though, a better picture would be even worse, since the extent of the damage would be more obvious. The justification for such damage here is more obvious, since, obviously, this is a bad situation, with no room for balanced growth. Although survival is possible, this is not what nature intended. Natural growth should be an asset, and efficiently directed to where it can be useful, which would most likely be much more balanced than this. Incidentally, this is a coastal redwood, which is the Official State Tree of California. This sort of pruning would be just as damaging to Western hemlock, Douglas fir or blue spruce. For that matter, it would be just as damaging to longleaf pine, Western white pine or Ponderosa pine. Ultimately, it is bad technique for any tree in any situation.