It's unacceptable to lie.
Jamie's friend was shot at a party so cops are questioning people who were at the party, and Jamie knows who did it.
Jamie doesn't want to look like a snitch in front of his friends.
Jamie makes the cops give him witness protection in order to tell them what they want to hear.
Jamie tells the cops that he didn't see anything and doesn't know what happened.
The man who shot Jamie's friend will not be able to harm anyone else in the future.
The person who shot Jamie's friend gets to run free and other lives are at risk.