[1] Prior to the passage of Proposition 128, people convicted of violent felonies, including murder, assault, kidnapping, arson, burglary, and robbery, were required to serve a minimum of 75% of their sentence before becoming eligible for parole.

The petitioning and campaigning for the measure are being led by the conservative group Advance Colorado, who also backed Amendment 80 and Proposition 130.

[2] The proposition appeared on the ballot as follows:[3] Shall there be a change to the Colorado Revised Statutes concerning parole eligibility for an offender convicted of certain crimes, and, in connection therewith, requiring an offender who is convicted of second degree murder; first degree assault; class 2 felony kidnapping; sexual assault; first degree arson; first degree burglary; or aggravated robbery committed on or after January 1, 2025, to serve 85 percent of the sentence imposed before being eligible for parole, and requiring an offender convicted of any such crime committed on or after January 1, 2025, who was previously convicted of any two crimes of violence, not just those crimes enumerated in this measure, to serve the full sentence imposed before beginning to serve parole?There was no major organized campaign in favor of Proposition 128, though petitioning for the measure was led by the group Advance Colorado.

The state's official voter guide also offered the arguments in favor of the measure that it would increase public safety and ensure that justice is served for victims of violent crimes.

Opposition to Proposition 128 was led by the group Coloradans For Smart Justice[6] The official Colorado voter guide also offered the argument against the measure that it removes rehabilitation opportunities for inmates and would increase prison costs without reducing crime rates.