Friar Laurence as a member of the clergy of the Roman Catholic Church is clearly in the wrong for his performing a marriage ceremony for Romeo and Juliet. William Shakespeare, who was a closet Catholic exposes in this place some of the corruption of the clergy of the Church, perhaps in order to ingratiate himself with Queen Elizabeth, who was a patron of the theatre. For, in the Catholic Church marriage bans must be posted six months before couples are married, and no couple can marry until there are no objections to their marriage at the end of the six months.
This is the first of Friar Laurence's acts which break his vow of obedience to the Church. His making of certain potions would at least be frowned upon. Then, his giving of a vial of these potions to Juliet would clearly be brought before his superiors.
Evaluating whether an act is right or wrong is a subjective process, based on one's experience and set of morals. Shakespeare tells us that Friar Lawrence hoped to mend the feud between Romeo's and Juliet's families by marrying the young couple. Shakespeare suggests that Friar Lawrence accomplished this, but the outcome proved more tragic than Friar Lawrence imagined. The families were mortified by the deaths of Romeo and Juliet, but at the end of the play, Shakespeare insinuates that the suicides might stop the petty arguments between the families. Did Friar Lawrence want to create such a tragedy? Not likely. Rather he was motivated by his own personal desire to create peace.
The same might be said about Friar Lawrence's giving Juliet the sleeping potion. This was also a good plan gone bad. Yes, his ideas were deceptive, but he weighed the so-called sin of deceit against his hope for a positive outcome. Should he have more carefully calculated the things that might go wrong? Possibly. He might have had a backup plan that could have saved the young lovers, such as making sure that his message was delivered to Romeo explaining that Juliet was not really dead. But this could only be judged as an oversight not as an evil act. In other words, Friar Lawrence's head might not have been in the right place, but his heart was.
While the friar might not have planed for their deaths remember that his first plan was to tell the families of the marriage. If he had just done that instead of having Juliet fake her death then about four people would be alive. Romeo, Juliet, Paris, and possibly Lady Montague.
Friar was right to marry romeo and juliet, It shouldn't matter that the two families were enemys and friar wanted to help two people that were in love. Romeo and Juliet were in love and it's not like her mother really cared who she married anyway.So I think Friar was right to marry Romeo and Juliet.
It seems that the Friar acts generally out of good will, he attempts to help Romeo and Juliet. His plan does not work, though, as he's not able to tell Romeo that Juliet is not really dead. Just like everyone else, he is a victim of people and things he cannot control.
In the end, the prince absolves the friar of wrongdoing, calling him a "holy man" (V.iii.270), and blaming the deaths on the family feud and not the Friar.