Not exactly - there are cases where an unwilling soul can be used. It has to be from the user's clan/house, and is usually a form of sanction. The idea is that one has obligation toward his family, and death doesn't end them. So you can be dragged back kicking and screaming into the fold for the good of the family even after you're dead.

Note that most of the se restrictions are applied to what is considered as people. For more than a few dunmers, khajits and argonians are clever beast and not peoples, and what you're doing with their bodies and what passes for their souls (they're not peoples, so no 'true' soul according to that point of view) isn't an issue. Some would even dump humans into that category.