I have no real idea with Navalnvy, and only dim memories of news reports about Magnitsky which went into a little more detail, but I’ll tell you how I assume it operates: It’s basically mistreatment to the point that it’ll kill you, just slowly. Your cell’s cold all the time, in the arctic winter with no blankets. You get bad food and bad sleep and beatings and no medical care of any kind. Once your body starts to malfunction (Magnitsky started having kidney failure), they go on beating you severely enough to cause additional organ damage, but then just continue to put you in your cell day after day with no medicine. Basically, you’re going to die, but they’re drawing the process out enough that it’s indirectly, because of “medical issues” related to what they’re doing to you, instead of just from blunt force trauma or something. So it’s incredibly painful and long and drawn-out, a slow death of constant suffering from which you can’t escape or get any relief.