Actually I'm copying the current German constitution in that a bill of Basic rights is included within the Constitution, guaranteeing the fundamental rights that all citizens possess. I haven't had the time to explain it IC, but the Socialist Party does not have a stranglehold on power, and has to share it with a broad coalition of leftists, liberals, etc, who fear any attempt to establish a dictatorship. So the constitution will be the product of a compromise between all these factions, with the Socialists accepting a democratic framework (for the time being, at least in their mindset), and the others letting them make it very social-oriented. 
And the thing is, the German constitution does guarantee property, and I could see why the liberals and farmers might want to enshrine this guarantee. Furthermore, Persia just avoided a civil war, and the conservatives are understandably always on the brink.