I don’t believe in Karma (the New Age version, that is, which for the purposes of this discussion I'm separating from the Hindu and Buddhist versions thereof). Or the Threefold Law. Or any other attempt to stuff morality and ethics into a nice, neat proportionate package, which I’ll abbreviate as Karma/3FL. Karma/3FL states that if you do bad things, bad things will happen to you, and if you do good things then you’ll receive that good in return, sometimes in the same proportion, sometimes in some set multiple like three.
Lupa has written an excellent post about why bad things happen to good people, and vice versa, and what we as Pagans can do about it.