Some months ago the Internet was abuzz with discussion over whether or not sting operations against Planned Parenthood are moral.

These ongoing operations, conducted by Lila Rose and her associates working for Live Action, involved individuals pretending to be a pimp and a prostitute who lie to Planned Parenthood staff about the need they have for abortions and health-care services for their 14- and 15-year-old “workers.”

This technique led to exposing Planned Parenthood’s practice of collusion with pimps and prostitutes and their disregard for the legal mandate to report statutory rape and other violations of the law.

Catholics, however, are not satisfied simply with good results. We do not judge actions solely by their consequences. We understand that we should never do evil to achieve good. A good end does not justify an evil means.

So the question is: Were the Live Action investigators guilty of using immoral means to a moral end?

On the face of it, it seems so. After all, the Catechism states: “Lying is the most direct offense against the truth. To lie is to speak or act against the truth in order to lead someone into error” (2483). Quoting St. Augustine, it defines a lie as “speaking a falsehood with the intention of deceiving” (2482).

The investigators certainly were saying something false with the intention of deceiving, and thus it seems an open-and-shut case. Some conclude that they lied: It is wrong to lie; no matter how good the consequences, they should not have told lies to achieve their good ends. They were, it seems, clearly violating Church teaching.

Yet, in spite of what seems an obvious conclusion, many faithful Catholic theologians, such as Christopher Kazcor and Peter Kreeft, posted statements on websites in defense of Live Action. Other theologians, such as Christopher Tollefsen, William May and Germain Grisez, posted statements or gave interviews lauding Live Action’s intentions but condemning their actions. The “comments” sections of numerous blogs raised myriad questions about the morality of spying and undercover police investigations, the giving of false passports to Jews during World War II, and about many passages in Scripture that seem to indicate God’s approval of some lies (such as the Hebrew women lying to Pharaoh about why they didn’t kill boy babies).

Why the confusion? Again, shouldn’t it be an open-and-shut case, given what the Catechism states? Surprisingly, the Catechism is, in some sense, one of the sources of the confusion.

In the 1992 first edition of the Catechism, the sin of lying was defined quite differently from the final and official version of 1997. It stated: “Lying is the most direct offense against the truth. To lie is to speak or act against the truth in order to lead into error someone who has the right to know the truth” (2483). This definition leaves a great deal of latitude for stating falsehoods to those who do not deserve to know the truth, such as Nazis seeking to kill Jews hiding in someone’s attic.

With these two different definitions of lying, the Catechism reflects a debate that has been ongoing since the early days of the Church.

Several of the early Church theologians, such as Clement of Alexandria, Origen and Hilary, maintained it was moral to tell a falsehood to deter someone from killing an innocent human being. Augustine famously broke with his predecessors and with his contemporary Jerome and condemned nearly all falsehoods, in word and deed, even falsehoods told just to get a laugh (jocose falsehoods).

I think it a rather large nose under the tent that Augustine allowed a man to lie who was threatened with homosexual rape. It is not hard to think that threat of other actions might also warrant lying, although neither Augustine or Aquinas thought so.

John Henry Newman condemned nearly all falsehoods, except those told by lawyers to protect secrets told them and by priests to protect the sanctity of the confessional. I believe these exceptions indicate that an absolute ban on telling falsehoods is next to impossible to sustain.

Aquinas’ position on lying is based on a view of the purpose of speech that might not be accepted even by some of those who agree with him on the morality of lying. Aquinas didn’t convince everyone. Those who invented the theory of mental reservation (not saying aloud all one has in one’s mind) defended the telling of falsehoods in some situations.

Newman acknowledged that the question was an open one at his time and that those who defended the telling of falsehoods were not rejecting Church teaching. The opinion of Aquinas has remained as the stronger one, but the appearance of the phrase “who has the right to know the truth” in the first edition of the Catechism indicates that the issue of the morality of telling falsehoods to evildoers was not settled at that time and even at that time it was approved.

So what are we to make of the change between the first version of the Catechism and the final, authoritative version?

The Church has not explained why the phrase was excluded in the final version. Certainly, it is not an unreasonable explanation that it was an error to include the phrase in the first place and to claim that now the issue is settled. Yet, there are also reasons to believe that the Church did not intend to settle the issue, that it intended only to provide what is the “more probable” teaching, the one held by more of the reputable theologians who have addressed the issue.

Had it wanted to settle the issue, the Catechism could have done so more clearly and emphatically by included statements such as: “It is always morally wrong to tell falsehoods even to deter those who are intent upon serious wrongdoing.”

The Catechism could also have clarified whether it is always wrong to use conventional falsehoods (such as saying “I am fine” when one is not fine) or telling jocose falsehoods. (Although Augustine and Aquinas condemn all such lies, they hold that such lies are venial not mortal sins.)

The Catechism could have listed spying and undercover sting operations as the sort of actions that violate the Eighth Commandment, as it is careful to list different kinds of actions that violate the other commandments.

The silence of the Catechism about the kinds of actions (conventional falsehoods, jocose falsehoods, spying, etc.) that many Catholics approve, is telling. Moreover, many saints have engaged in false significations; for instance, the martyrs of recusant England and those who harbored them.

How should this issue be resolved? I believe theologians and philosophers need to engage the issue very energetically. (I recently attempt such an engagement in the June/July edition of First Things). Both those who would condemn all lying and those who approve of telling falsehoods in some situations need to define precisely what a lie is and why it is wrong or why it is not always wrong. Only then we will be able to determine whether what Live Action did was moral or immoral.

I think the history of the Church’s teaching and the current state of the Church’s teaching on the morality of telling falsehoods to evildoers shows that it is an unsettled teaching.

Thus, I think we can say with some confidence that the Live Action investigators did not violate settled Church teaching on the matter. I think Catholics involved in spying, police sting operations, and military deceptions also are not violating settled Church teaching.

They must examine their consciences to determine if they believe God is calling them to engage in such activity. And meanwhile, theologians and philosophers should get busy.

Janet E. Smith, Ph.D., holds the Father Michael J. McGivney Chair of Life Ethics at Sacred Heart Major Seminary in Detroit, Michigan.