We know that even in the Islamic countries the people who are often elected into the parliament are not of Islamic mind. They tend to be secular. Can we entrust them the responsibility to legislate for us according to the laws of the religion? How can give authority to a member of parliament to interpret Islam? It will be like the British Parliament which even passed homosexual laws? .How can ever a Islamic minded parliament established through vote? I believe a better option is the concept of Majlis e Shoorah introduced by General Zia Ul Haq in Pakistan or the institutes like Islamic Ideology Council.
The question is that the collective matters of Muslims have to be decided with their mutual consent. And it is only the majority of the Muslim populace which elects the members of the parliament. If they choose people who do not consider the Islamic view much important they may not be voted in the office. If the Muslim populace decides to vote some party or person in the office it gives them the right to make laws which they will follow. After all, the parliament makes laws and we abide by them all the time. All the members of the parliament do not know what the problems are relating to the health and nourishment. They do not understand what medicine is more harmful than beneficial. But they decide on the matter using the interpretation of the experts of the related fields. You have rightly said that they can use a body or council of scholars to work on this and provide the parliament necessary guidance.