Richard,
I'm very impressed with the Imperial Constitution you've developed. It seems like something that could potentially come about in the OTU if the Parliamentary Monarchists and Republicans in the Moot were to combine forces (
http://wiki.travellerrpg.com/Imperial_Moot). I'm particularly pleased with Article 5, Section 13, which seems to effectively block the Imperial government from trampling around in many key areas. Strangely, however, this article seems to have two sections 3, 4 & 5. You might want to edit it a bit. A few minor concerns:
1. The interests of small-population planets seem to be treated equally to those with large populations. Or maybe I'm reading this wrong. Is the moot more like the Senate or the House? Nowhere do I see any indication that a noble's vote carries a weight proportional to the population he "governs" or the revenue he "raises", but it could be the case that I just missed it.
2. Likewise, is it possible to stack the moot by creating lots of Imperial corporations?