The background: The Idaho Legislature has many quirky rules and processes that have developed over the state’s 136-year history, but one has made big waves this session: radiator capping. The maneuver was used on three contentious bills this session:
• House Bill 516, the anti-IEA bill, swapped in the text from House Bill 745. The previous version of the bill had been held in the Senate Commerce and Human Resources Committee.
• House Bill 659, which was replaced with language from Senate Bill 1247, mandates local law enforcement enter into cooperative agreements with Immigrations and Customs Enforcement (ICE).
• House Bill 670 was gutted in favor of the language in House Bill 389, which deals with taxes raised by cities and fire districts, as well as building capabilities for urban renewal districts.
• In Idaho jargon, radiator capping involves swapping out the text of one bill and replacing it with another. “Think about a car with parts that have been entirely replaced — except for the radiator cap,” said Idaho Education Association Associate Executive Director Matt Compton. “Would you call that the same car? Of course not.”
• Other states have their own colorful terms for the practice, like “hog housing” and “gut-and-go.”
How it works: Radiator capping takes place in the amending order of the House or the Senate, when bills may be changed on the floor by the entire body.
• It can be considered a friendly or hostile maneuver. The swap made for the anti-IEA bill, for example, was approved by the original sponsor of the bill. But Rep. Jordan Redman (R-Coeur d’Alene) crammed in the ICE-friendly legislation over the objections of that bill’s original sponsor.
Why it’s problematic:
• Radiator capping bypasses the traditional committee hearing process in which Idahoans can testify for or against legislation that affects them. House Bill 745 had a multi-hour hearing in the House Commerce and Human Resources Committee. The radiator-capped House Bill 516 was never opened for public debate.
• It foments distrust in the legislative process.
• It can lead to inter-chamber warfare.
The bottom line: There’s a reason this tactic used to be rare — it’s not the way Idaho has traditionally legislated. But during the 2025-2026 legislative session, which saw a record number of bills flying through the Statehouse as hardline lawmakers attempted to consolidate and concentrate power, the old norms are out the window.
• As Idaho Statesman writer Bryan Clark put it in an opinion published Thursday after House Bill 516 passed, “Perhaps it’s more accurate to describe it as ‘the coward’s maneuver’ rather than ‘radiator capping.’”
