Most would agree that when man's law directly contradicts God's law, God's directives must prevail. For example, thousands of Christians were martyred because they refused to worship the Roman emperor. It is almost universally accepted that these people did the right thing; in fact, many have been canonized as saints.
Other Christians have been praised for refusing to take the lives of others, or their property, or spread anti-Christian propaganda, etc. as mandated by law.
But what about stopping a serial killer who has taken more than 60,000 lives? How do you factor in the 15-20 babies who will not be killed today by this monster -- and the same number every day now on?
Where do you draw the line between Biblically justified and unjustified under these circumstances?
I would go with the good ol’ Ten Commandments... thou shalt not kill
That's the dog that doesn't hunt. Tiller already flew in docs who operated in his absence. It's already been reported that business will go on at the clinic with these same docs just getting more hours. Roeder didn't save any lives, he just took one.
I am reminded of Johnathan Edwards sermon. His text was the following:
Christians need to wait upon the Lord. We don't always see justice, but in due time justice will be given.