I don't believe in it. I used to but noticed too many inconsistencies. Some bad people prosper and some good people suffer; also the other way around. Seems very random to me. Of course, bad and good are also subjective. Like superstition, karma only has power over you if you are bound by the belief in it (power of suggestion can wreak havoc on the subconscious). Just my opinion. This, just based on my own personal experience and observations, not from any book. I could be wrong. You never know. I just haven't observed it, personally.