It could be interesting though, image the laws starting to include the usual: "The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119"
Although I rather like that idea, the problem is not actually how the laws are written, but the language they are expressed in. When you try to accurately and unambiguisely describe something, you run into the problem that English may appear simple, but is capable of incredible nuance in the hands of a skilled author - and lawyer. This is why you end up with "legalese" instead of garden variety English: you state X, than you have to explicitly qualify that when you say X, you don't mean Y and do not infer Z, followed by the problem that even your qualifying sentence actually needs a qualifier of its own to exclude any more creative interpretations.
English is a fantastic language for humour, jokes and leaving things unsaid but still convey what you mean, but the consequence is that it's a swine to really pin something down in writing :).
Legal German, for instance, is much simpler because German is by its nature more descriptive and precise. Of course, as a living language it also has its fun parts (otherwise politics would be nigh impossible) but you don't immediately end up with seven ways to interpret a sentence. As a consequence, expressing a law in German is a shorter exercise than one in English and not quite such a mind bender to read (if you speak the language, of course :) ).