A close-up of an 1876 copy of the Colorado Constitution — looking at Sec. 26, which contains an exception under which slavery could be used as punishment for a crime — at the Stephen H. Hart Library & Research Center in Denver.

(P. Solomon Banda/AP)

It had no organized opposition during the campaign season, but Amendment T found opponents on election day. In Article II, Section 26 of Colorado's constitution, slavery is banned with one exception, for the "punishment of a crime." The ballot measure proposed to eliminate that exception clause. 

The final vote was close, and more than a week after the election, it was called -- voters rejected the measure.

There are a couple of theories why, including that the ballot language was confusing. Will Dickerson is with the Denver nonprofit Together Colorado. He helped lead the Yes on T campaign. Dickerson spoke with Colorado Matters host Ryan Warner.