Hunting, fishing, camp, and utility blades of any length are exempt provided they are carried openly and the individual in question is at a campsite or in the mountains and can articulate a reasonable explanation for why he has it on his person.

State of Colorado specifically permits daggers and dirks as long as blade length is under 3.5", but Denver does not recognize this statute and measures the entire cutting edge rather than blade length. That would turn a legal 3" boot knife into an illegal 6" weapon.

If Denver police notice a pocket clip they can ask to see the knife so they can measure it. If blade length is a fraction of an inch over 3.5" some officers can and will arrest you for carrying a "concealed" knife even though it was in plain view. These cases are frequently dismissed when they go to court.