Who Watches The Watchmen?

It was just the title of the graphic novel series on which the movie Watchmen is based. It was a slogan raised by the fictional people of New York in the graphic novel who had protested against the Watchmen and masked vigilantes. The people wanted more government control over there activities and to be rather protected by badges and not masks. It was their concealed identities and their actions beyond the code of law which made them suspicious to the people who would rather have people that they could trust in charge. The fear and suspicion made them say "who watches the watchmen" which means if Watchmen keep on acting on their whims protecting them then who is to say if all their activities are ethical.