Amendment XIII

She was outside the W Union Square, and it was 29 degrees F.

In Harlem, at the 145th Street A, C, B and D subway station, by the 147th Street exit, someone has taped two tiny printed-out pieces of text... It's the text of the XIIIth Admendment to the U.S. Constitution, which states:

XIII: Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.

It's marked up and highlighted as above. Why?