High clearance rates don't mean police are good at their jobs. Police in Japan can hold a suspect for 23 days without charging him. During this period, they try to get a confession out, using techniques such as sleep deprivation. Furthermore, once you get to trial, it is usually with only a judge, not a jury. All levels are pushed to keep up this high conviction rate. So just because the rate is 98%, this doesn't mean justice was actually served at that rate.