I recently came across an article pairing rap lyrics with more formal poetry. Here are a couple of samples:
FOUNDING FATHERS/EARL SWEATSHIRT
We hold these truths to be self-evident
Say hi to the Ritalin regiment
("Declaration of Independence" and "Pigions")
Whose woods these are I think I know
Creep with me through that immortal flow
("Stopping by Woods on a Snowy Evening" and "Thug Passion")
On a more serious note, there is a growing body of law surrounding the use of rap lyrics as confessions or other evidence in criminal trials. In the past two years, rap lyrics have formed the basis of convictions in more than three dozen cases.
For more on this subject, check out Confessions in the Courtroom; Silence, Confessions, and Improperly Obtained Evidence; The U.S. Court of Appeals and the Law of Confessions; and Confessions, Truth, and the Law.