Because Wicca puts so much emphasis on personal responsibility, there are very few laws per se. Even the primary ethical statement is not described as a law, but rather a rede, or guideline, by which you can measure your actions. Let's look at the Rede first, in a couple of different wordings:
" 'Do what thou wilt' shall be the whole of the Law. Love is the Law; love under Will."
- Traditional Gardnerian; taken from Aleister Crowley and ceremonial magick
"Have fun in this lifetime, but don't hurt anybody."
- a paraphrase by a fictional Wiccan character, Diana Tregarde, in Mercedes Lackey's Burning Water
There are two separate parts to the Rede as it is normally worded, in modernized language: if it harm none and do as you will. This isn't the licence to freedom that some people make it out to be.
First of all, let's look at the words "harm none".
One, "none" includes yourself, so you have to look at any action you take and make sure it contributes to health, happiness, growth, and self-respect.
Second, it says "harm" none, not "hurt" none, so the Rede isn't an excuse to step back and allow someone to abuse you or someone you love without your taking any steps to defend yourself. You can politely tell someone "I don't think it's respectful for you to do that" and perhaps hurt their feelings, but you harm them in the long run by not stating how you feel about their actions honestly. Just respect the other person as a person who also needs to grow and learn, and you're probably walking fairly close to the spirit of the Rede.
The other half of the Rede says "do as you will". What you will is not necessarily the same thing as what you want.
That's not always obvious, so let me clarify. I may want to stay up and play on the computer all night (as I'm doing right now writing this, but let's not quibble about technicalities). But my will, what I choose with both heart and mind to do, is support my family by not only holding down my tech support job, but by doing it to the best of my ability. That requires me to act in will and put aside my playing in the interests of getting enough sleep to function effectively at my job. At the same time, doing my will means that I'm doing computer tech support at a help desk where I actually enjoy what I'm doing, and not moving into high-level networking where, while I'd make more money, I'd also be bored silly and not following what sings to me. Doing my will involves loving the number of people I choose and the genders I choose, without listening to what society says I ought to do, because I know where my heart is and who I choose to give it to, and what makes me truly happy.
So following this portion of the Rede means knowing what I truly choose to do that has my long-term interests in mind. It means listening to the voice within me that cries 'yes' when I am on the right path for me, not necessarily what seems like the thing I ought to do to keep up with what society expects of me. And finally, it means having the courage to act on those convictions once I dig within myself and determine what they are.
This one takes less pontificating, I think: simply put, what goes around comes around. The triple concept may not be exact in numeric terms, but most especially when you are claiming the powers of a Witch, what you do affects others. We're all interconnected. And with claiming your power to change comes claiming your responsibility for what you do. So no matter how the numbers stack up, it's wise to live as if any action of yours will snowball. For the Gods have twisted senses of humor, and usually ensure that this comes more or less true. :)
This comes more from ceremonial magick, and simply exemplifies what I talked about in discussing the Rede. All magick comes down to four things: Know what you truly desire, dare to believe in it, will it to be by belief and congruent action, and then walk away, knowing that what you have set in motion will come to fruition in its own time.