Gray areas between the evil black and the pure white

Justice and evil is not absolute.
A Law Abiding Citizen should be praised,BUT "law" is formulated by human.
尼克 on behalf of a group of people who is only the pursuit of efficiency and reputation.
So Clyde,at first,kind of meet the audience of a strong sense of justice.
But then the story began to get out of control,,,which made us confused...
In fact, that is so.
Gray areas between the evil black and the pure white,and the movie reflect the real world.
I do not think it was a happy or sad ending.Just like the title,my feeling was gray,too.