What is the ruling on joint ownership of property between spouses upon the marriage contract, if it later becomes apparent that it is not permissible in Sharia?

If a condition is stipulated in the marriage contract to divide properties equally between the spouses, this condition is void and not approved by Sharia (definition) rulings, unless it is with the consent of both parties. The contract itself is valid, but the condition is annulled and does not invalidate the contract. The spouses must agree to apply Sharia rulings, and they can stipulate in the civil contract the independence of each spouse's ownership from the other.