A Muslim in general is required to obey the law of the land he/she resides in and to follow all agreements they live under.
If the law conflicts with something that is obligatory in Islam, then it becomes incumbent upon them to move to a land where there is no such conflict. Allah says in the Qur'an:
Is not the earth of Allah wide enough so that you could migrate? Nisa':97
In democratic countries where the people get a say in deciding the laws, it becomes incumbent upon the Muslims to work within established channels to change those laws, because this is legal and permitted and encouraged. Doing so outside these means is expressly prohibited religiously.
When a religious action is not obligatory for a Muslim (e.g. praying in public) then there is no conflict. Women (and men) to cover their `awrah in public is obligatory; so is eating halal. Eating meat itself is not obligatory however, of course. Halal is a wider term than just for meat.