Idaho stop refers to policies that allow cyclists to treat stop signs as yield signs, and in some jurisdictions, red lights as stop signs. Both first became law in Idaho in 1982.
Rationale
Cyclists usually cannot travel fast enough that a complete stop is necessary to adequately assess, and safely proceed through an intersection.
Coming to a complete stop in these situations may present more danger, as the cyclist remains vulnerable inside of the intersection for much longer while picking up speed.
Stop-as-yield laws incentivize cycling traffic through slower, local streets by reducing the burden and danger posed by stop-controlled intersections.