Nick Fury (Samuel L. Jackson) and his S.H.I.E.L.D. organization has been at the center of the Marvel Cinematic Universe since Robert Downey, Jr. became Iron Man in 2008 -- leading to the four-year assembling of "Earth's Mightiest Heroes" known as Marvel's The Avengers.
Captain America: The First Avenger was a throwback to those Saturday afternoon matinees, where you knew who the good guys and bad guys were, and that the good guys win in the end. In this case, it was Steve Rogers, the kid from Brooklyn who becomes the super-soldier Captain America, the symbol against Red Skull's tyranny and oppression during World War II.
Now, Captain America: The Winter Soldier finds Cap (Chris Evans) struggling to life the 21st century after a 70-year nap, where the world is no longer black and white, but gray and green all around -- especially when it comes to defending the red, white, and blue known as the United States of America. Unlike Fury and fellow Avenger Black Widow, Cap isn't comfortable being morally flexible, doesn't believe that the ends justify the means, yet always know where to draw the line.
However, Batman, Dirty Harry, The Punisher, Wolverine of the X-Men, and 24's Jack Bauer are willing to cross lines and break laws in their pursuit of justice -- sometimes revenge -- because they operate under a vigilante code of ethics: putting them into the category between hero and anti-hero.
Captain America: The Winter Soldier is in the same category as 24, Burn Notice, Person of Interest, and now Marvel's Agents of S.H.I.E.L.D. are in: the public may no longer trust and believe in a government that is supposed to be for the people and about the people, not about politics and power, where our laws and legal system doesn't protect the innocent but the guilty and corrupt instead.
Still, Captain America: The Winter Soldier shows why Captain America is the literal 'SHIELD' for liberty, patriotism, and freedom: he is the true representation of the United States of America.