How has the director, Kathryn Bigelow, use film techniques to portray injustice and inequaity?

Hello,

Could anyone kindly present any ideas on how the directer has implemented film techniques to represent injustice towards black Americans and what effect of these techniques have on the audience.

Techniques like camera angles/shots, sound/music, voice over, symbols etc. will be highly apprecaited!

Thank you, and I hope to hear back from you.