Can Policemen Lie and be Good Christians?

This is an area I have wanted to explore. On an argument on same sex marriage Robert George ends with this observation

Back to Michael Perry's post, he says that it "bears emphasis" that most American Catholics violate what Michael likes to call "official" Catholic teaching on contraception. That is, no doubt, true. It has the same relevance to the question of the truth and authority of the teaching that the fact that most American Catholics violate the Church's teaching on lying has. (Evangelicals seem to be in the same boat on this one, by the way. It seems that utilitarianism has seeped so deeply into the public's understanding of ethics that even Catholics and Evangelicals--who are supposed to be believers in moral absolutes--tend to think that lying is morally acceptable where it serves the "greater good" or is the "lesser evil.").

Now I think George is right on this as very sound general principle. But strangely I have never heard this fleshed out. Thus I don't know all the answers to this. It would seem to me a average Catholic Priest would be confronted with a ton of cases in his flock where he would be confronted with this.

Lying is view as an acceptable part of business in various professions that have tons of Catholics. Here are few examples.

A Catholic Police Officer poses as either "hooker" or as a customer in sting operations in order to curb prostitution. This involves lying and deception

A Catholic DEA agent or policemen are involved in major deceptions in drug cases where not to do so would even put their lives in danger.

Undercover operation with the FBI and CIA involved by necessity lying and deception.

In order to get a "confession" from a person in custody lying is often used. For example "your buddy has already ratted on you and so help yourself tell us you did it".

A good many Police agencies have very good trained Christian ministers on staff. How do they deal with this?

Let us look at other professions. What about journalism that involves undercover work. The now famous Acorn tapes for example.

Again I don't know the answer to all the above. Maybe all of it is sinful and prohibited. But if it is it seems there is very little talking about it.

Just something I was thinking of this morning. I am a pretty educated Catholic I think and have to admit I don't the answers to the above.