AMJA represents the highest Islamic authorities in North America. The members hold a Ph.D. in Islamic Shari’ah. They have the power and authority to issue
“. . .fatawa (religious formal opinions or rulings) pertaining to the cases and queries submitted to the Assembly according to the rulings of Shari’ah.” In addition, the AMJA, conducts “. . .lawful researches and studies on the circumstances of Muslims in the American society and the economic, social, intellectual, and educational problems Muslims recently face in such a community so as AMJA manifests their suitable juristic solutions and supervise their application.” Amjaonline
In the excerpt below taken from the AMJA website one of the experts in Islamic Shariah is telling American Moslems to follow American law only when doing so does not contradict the principles of Shariah.
All praise be to Allah, and may His peace and blessings be on the greatest messenger, Muhammad.
As for your question about the local laws that are not in conflict with the share’aah, they must be respected particularly when they agree with the objectives of sharee’ah such as the seat belt, speed limit and such laws that aim to preserve life and property.
As for the income tax, and such laws that are not consistent with the sharee’ah (taxes are considered by many not consistent with the US constitution either), it is different. A Muslim will follow such laws to avoid the bigger harm to himself and his community, and based on the balance of benefit and harm, it is prescribed for him/her to abide by such laws. (Taxes are generally forbidden in Islam with some exceptions in certain cases)
The difference between the first and second groups of laws is that with the first group, you abide by them while inwardly respecting them. The second may not be respected or valued inwardly because they conflict with the sharee’ah.
The issue of polygamy (polygyny) is a complex one, but those are some guidelines:
Allah knows best.