First and foremost, the thing Tom thinks he is justified in doing is telling Wilson that Gatsby was the one who hit and killed Myrtle (pg. 187)..  Tom thinks that he is above everyone else in society and can do whatever he wants.  Tom sees himself as superior to others and thinks he should be the 'good person' in everyone's business.  He thinks that he alone knows the right way for everything and always knows what is best for everyone.  In his mind, Tom did the right thing by telling on Gatsby because he views himself as the 'good man' in everyone else's business.  If Tom had not told on Gatsby, he would have been the one in trouble.  Wilson would have assumed Tom was driving the car and hurt Tom instead of Gatsby.

          Also, Tom was in love with Myrtle.  Tom feels that the person who killed his love should be brought to justice, making it right for Tom to tell on Gatsby.  He probably knows that Wilson will hurt Gatsby in some way, but thinks it is right because Gatsby has caused him pain by killing Myrtle.  Tom may not want to punish Gatsby first hand because then Daisy will be mad at him.  Now that Daisy is the only women he has left, he cares more about her and her feelings.  To avoid punishing Wilson himself, Tom sees a perfect opportunity to get back at Gatsby and in a way ‘hires’ Wilson to do the dirty work  Also, Tom's decision to tell on Gatsby could be influenced by the fact that Gatsby was having an affair with his wife.  This probably made Tom mad and he wanted to show his anger towards Gatsby in some way.  He decides to tell on Gatsby because he has caused him much pain with the whole Daisy situation.

There are many other places in the book where Tom thinks what he is doing is justified.  In the very first chapter, when Nick first meets Tom, Tom shows us his rough personality.  Tom tells us about the books he reads.  These books are about how the white race is superior to all other races and it needs to be careful because it one day may be taken over by another race (pg. 17).  This tells us that Tom believes in these beliefs and he thinks that believing this is justified.  Also, the hint we get about Tom breaking Daisy’s finger (pg. 16) and the first hand experience of Tom breaking Myrtle’s nose (pg. 41) show us how Tom thinks that everything he does is justified.  Tom thinks it is ok to abuse women like this, even though it is totally wrong.

Tom thinks he is justified to have an affair with Myrtle, when in all actuality it is wrong.  Tom brings Nick to meet Myrtle right after he meets Nick, which makes me think that Tom thinks that what he is doing is right (pg. 30).  Also, when Daisy, Nick and Tom are having dinner in the first chapter, Tom talks to Myrtle on the phone (pg. 19).  Talking to his mistress when he wife and company are present seems like he thinks that what he is doing is right.

Teresa