Limits of the legislative powers of the caliph

Question

In a comment to this answer, user Uma states (picking up an example about fizzy water I suggested):

The limits ordained by religion are that the caliph shouldn't prevent doing an obligatory religious duty, and he shouldn't permit any haram action ... obedience to him is obligatory unless he commands disobedience to Allah. If he wants to ban fizzy drinks in turquoise cups he can, and the muslims must obey him

This is somewhat surprising to me; I expect that there are certain limits in sharia as to how much the caliph can restrict the freedom of his subjects. It certainly seems to be recognized in shariah that the governing organs can issue regulations such as traffic law, mercantile law, etc. That raises the question:

Which legal limits (as opposed to recommendations or exhortations) are there to the right of the caliph to penalize or criminalize otherwise halal behavior?

To give an analogue to what I'm looking for from a system of law I'm more familiar with: in modern law, the role of limiting the power of the governing organs of the state falls mostly to the constitution of a country, and banning fizzy water would go against the basic right of personal liberty enshrined in many constitutions. Limiting that right would require a collision with a constitutional duty of the state (fizzy water would not generate such a collision), and would thus be unconstitutional.

Answer 1

It is quite obvious that the caliph has the limits of his power within the strictures of Qura'an and Sunnah. Anything beyond would be sinful activity and hence accountable in the court of Allah. The Absolute Sovereign and the Ultimate Ruler here is Allah. Caliph is just the custodian and implementer of these laws.

However comparing the western constitutional limitation with those of the Sharia'a is a reflection of sheer ignorance. Constitutions are man made laws which do not have the capacity or the depth to be comparable to the Divine Laws.

Mad made law, can be flouted in secret, whereas there is no such possibility in Divine Law. The fear of Allah, His omnipotence, His Omniscience obviates all such possibilities. Man made law depends on the proof for dispensing punishment whereas Divine law exhausts all possible avenue of compassion to avoid the punishment. Therefore, Divine Law is more Human-friendly and just that any Man made law ever.