While I've never done it myself, or seen it done for that matter, I've read that if the individual committing Hari-Kari is off by just the slightest fraction with the knife, the wound is so debilitatingly painful that the person can only lie there in agony until dying of shock or bloodloss, usually about an hour or two later.
Sadly, the United States has to endure this painful agony for another three years, eleven months, and two weeks.