In addition to the fact that you will have an entire state on your side, as Dick Locke points out, and the fact that not using plain english can land you in some dire consequences, as Tim Cummins points out over on Commitment Matters, there is the fact that obscure language increases the risk of failure. If no one understands what they are meant to be doing, a dispute is more likely. Contracts need to be clear, so write them in plain English.