That makes sense. Possession of a machine gun (without a license) is a Colorado felony under CRS 18-12-102.
I can't, but having worked in a jail for a few years, I've seen it happen. BUT, come to think of it, every time it happened that I saw it was a crime against both the state and federal government. For example, once there was 2 "kids" (younger than me), that were suspected of possessing machine guns. The local officer brought them to the room in the jail where the officer gets all the personal details, and collects the belongings of his/her detainee. He called the ATF and asked them if they had any interest in them, which of course they did, and they were at the jail within an hour.
The local officer ended up charging them with nothing, since the ATF took custody of them.
I don't think so:
So I guess it's a question of, if you're "only" breaking federal law, can a state agency or an agency of a subdivision of the state arrest, detain, or otherwise hold you only on that charge, until the feds show up?
16-2.5-101. Peace officer - description - general authority.
A peace officer may be certified by the peace officers standards and training board pursuant to part 3 of article 31 of title 24, C.R.S., and, at a minimum, has the authority to enforce all laws of the state of Colorado while acting within the scope of his or her authority and in the performance of his or her duties, unless otherwise limited within this part 1.So this section establishes what authority a peace officer has, and federal law is not part of it. It then goes on to establish authority for "police officers" vs "sheriffs deputy's, state patrol, town marshals, etc. None of these types of peace officers have any more power than to enforce Colorado law. CRS 16-2.5-147 specifies power for "Federal special agents" and they have some different powers.
Additionally, any federal LEO acting withing Colorado law must release any suspect over to a Colorado peace officer. There was a case cited in the annotations for CRS 16-3-110 where some LEO (seemingly federal because the statue was about federal LEOs) outside of their jurisdiction stopped a suspect in a traffic stop. The entire contact was ruled invalid by a US Appeals court because LEOs outside their jurisdiction can only stop a suspect if the "crime" they witness is in fact a "crime" under Colorado law.
16-3-110. ANNOTATION So a Colorado Peace Officer cannot detain/arrest anyone for anything that is not a Colorado crime.
When officers stopped driver for a traffic infraction outside their jurisdiction, they violated subsection (2). Turning without a signal is a traffic infraction, not a felony or misdemeanor, under Colorado law. United States v. Gonzales, 535 F.3d 1174 (10th Cir.), cert. denied, __ U.S. __, 129 S. Ct. 743, 172 L. Ed. 2d 740 (2008).