Why the Law of Three sucks.
The Wicca Law of Three states that whatever you do will be returned to you three fold. Allow me to discuss this with you.
First, the universe does not generate karma, you do. The universe only creates it for you due to your anticipation of it. I will try to explain this.
Consider a lion killing a zebra. The lion committed a horrific act as far as the zebra was concerned, but no one would say that the lion would receive any bad karma from the act. The lion did not have any thoughts as to doing anything wrong. The lion has no karma coming from this act.
For you to receive karma, good or bad, you have to anticipate it. Think of all the infamous serial killers. They were never caught because they believed that they were not doing any wrong. It has to be a conscious anticipation on your part. If you feel you have done no wrong, there will be no karma, the same holds with good acts.
A little background for those new to this. The religion Wicca was created circa 1950 by Gerald Gardner and others around 1950 when the English Witchcraft Laws were repealed. The term wicca and wicce prior to 1950 referred to a male sorcerer. You cannot find anywhere a verifiable reference to wicca prior to 1950 that defines wicca in any manner close to the religion it is today. If anything Wicca is the worlds newest religion, not the oldest. Some of the Wicca practices go way back, but the same applies to all religions.
Gardner and others took witchcraft, which is an act, not a religion, and added a lot of sugar coated rituals and practices to make witchcraft appealing to those living then and hopefully defuse some of the negative connotations which were given witchcraft by competing religions. Witchcraft is an act of using natural forces to create your desire, a natural act for natural forces.
So, if you do not expect positive or negative karma, there will be none. If you expect good or bad karma you will receive it because due to the creative forces of the universe, you expected it, and the universe complied by creating it for you.