House approves bill targeting algorithmic rent‑setting after extended floor debate

DENVER — The Colorado House on March 25 approved House Bill 1004, sponsored by Representative Peter Woodrow and Representative Mariah Mabry, a bill that bars certain software and services that the sponsors say are used to coordinate residential rental pricing among competing landlords.

Supporters said the bill targets technology that can replace traditional collusion and quickly raise rents statewide. Representative Mabry and Representative Woodrow described committee and federal findings that algorithmic price‑setting contributed to higher rents, and they said the bill narrows liability for ordinary landlords while enabling state enforcement against software companies and clear instances of collusion.

The core provisions adopted clarify that a software provider may not sell or market a product with the intended effect of recommending or setting rents for two or more landlords where the same or substantially similar data or analysis is used to set those recommendations. An amendment adopted on the floor tightened landlord liability: landlords are liable only where they knew or should have known the recommendations were part of a price‑fixing scheme and the circumstances suggest knowing participation. The bill also includes carve‑outs for publicly available estimate services such as listings or Zestimate‑style estimates and for multiple listing services (MLS), and it states that the new statute supplements — not preempts — existing state and federal antitrust law.

Floor amendments adopted included language clarifying landlord liability standards, a provision limiting liability of software sellers when the same algorithmic code is sold with different data, a carve‑out for public estimate products, and an explicit non‑preemption clause so the law supplements existing antitrust remedies. Sponsors said those changes came after negotiations with stakeholder groups, including landlord associations and realtors, to narrow the bill’s scope.

The floor debate was both lengthy and partisan. Sponsors argued that Department of Justice actions and a White House report showing algorithmic pricing added roughly $136 a month on average in Denver justify a legislative remedy rather than waiting for protracted federal litigation. Opponents said existing antitrust law already bars collusion, cautioned that adding new causes of action could spawn litigation and compliance costs for small landlords, and said supply constraints — not software — are the main drivers of high rents in many areas.

Several motions to send the bill back to committee or to add additional study were defeated. The bill passed on final passage; the transcript does not specify the final recorded vote tally for the floor passage.

Supporters said the bill provides state law enforcement and consumer‑protection attorneys a usable tool to pursue companies that enable coordinated price discipline. Opponents said the measure risks unintended litigation and could impose compliance costs on small landlords. Implementation now shifts to the attorney general and courts to enforce the new cause of action and for the state’s courts to interpret the knowledge standard adopted for landlords.

Votes at the end of the day showed the measure was adopted on the floor. Sponsors indicated they expect the bill to be reviewed further in the Senate.