Muslim working in law enforcement in a non-Islamic 
country
Question

                I have a question regarding the permissibility of becoming a 
law enforcement officer in this country that does no follow 
sharee 'ah. Is it haraam to be enforcing laws that have not 
been developed by our Creator Allaah and His holy 
Prophets (upon whom be peace)? Even if it means enforcing 
laws on non-Muslims?
Partciluarly, is it permissible to enforce a law like punishing 
someone for speeding on the highway? What about allowing 
someone to drink alcohol if he is over 21 but not if he is 
under 21? Even though this is not Islamic, should a Muslim 
allow such behaviour among non-Muslims? Of course, 
Muslims will be accountable for these haraam actions in the 
Hereafter, but is it okay to let non-Muslims do this?
Praise be to Allah.
If a Muslim is able, through such work, to fight evil and oppression, or to 
prevent or reduce it by using the existing laws which may contain 
something of justice and decency, then it is permissible if his intention is 
to seek the pleasure of Allah. He may do this work even if it involves 
preventing only some people - but not all - from getting drunk, for 
example.
But if it involves enforcing laws that are unjust to people - whether they 
are Muslim or not - or enforcing something that goes against the 
Sharee'ah, like preventing people from wearing hijaab or praying, or 
giving some kind of protection to criminals, and so on, then this is not 
permitted at all.
The wise and clever Muslim knows from experience to what extent his 
work is in accordance with the Sharee'ah that is based on the common 
good and on preventing corruption. And Allaah knows best.