Ethical Problem

Utilitarianism's Solution

Lying: when is it okay or not okay to lie?

Lying, according to Mill, is a form of expediency. Expediency is defined as an action that is convenient, despite being possibly immoral.
Lying does not support the well being of an individual's happiness, the group's happiness, or society's happiness.
However...
There are instances where lying can cause more pleasure than pain for all parties involved. But...it is only in the form of denial.
For instance, it is okay to deny that you are hiding someone running away from a murderer, and it is okay to deny that your brother got into a car accident when your mother asks about it on her deathbed.