A teachable moment: Principal - Agent problem

[timelets]

Trump said: "If you get along and if Russia is really helping us, why would anybody have sanctions if somebody’s doing some really great things?"

The president is an agent of the american people in charge of, among other things, enforcing american laws. If the agent thinks that hacking a political opponent "is really helping us" and decides not to enforce sanctions, we have a classic Principal – Agent problem because the agent acts in his own interests, instead of the interest of the people (including those who didn't vote for him).