I'll eat my hat if Mike Leigh is pro life. However, it is the sign of a good artist when they can show the other side of an argument while still having their side win in an oh so subtle way.
You are absolutely right. Leigh goes out of his way to be objective and not making zealouts out of pro life and law enforcement officials. It's up to the audience to decide.
Mike Leigh belongs to a stridently leftist "post-Angry Young Man" school of filmmakers which includes Ken Loach and Stephen Frears. He's much less polemical than Loach however, and less conventional than Frears (who has made more commercial films such as High Fidelity, Dangerous Liasons and Mary Reilly, in addition to the likes of Prick Up Your Years, The Van, and Liam), so he's my favorite of the bunch.