If the officer handles it, he better empty it. I have seen many a cop put their finger on the trigger while handling a firearm.The firearm needs to be made safe if not in the holster for the safty of the officer and the citizen. The only way to do that is lock slide with no mag or empty the cylinder. If he happens to find one in the chamber when making safe that would be no different than pulling you over for speeding and finding the 10 pounds of pot sitting in the back seat. If safty is the basis for handling the arm, then anything in the process of making safe is fair game. When they find one in the chamber then they would at that point verify for legal compliance for open carrying a loaded weapon.
I do not necessarily disagree with you here...clearing a firearm is SOP.
However, a cop putting their finger on the trigger?? Especially of an UNKNOWN weapon??? At risk of smudging fingerprints possibly incriminating of an as-yet unknown crime? The excepted infringement upon the 4th amendment is to protect the suspect from shooting the cop. It is NOT to protect the cop from being a complete moron.
With your example, the 10 pounds of pot is clearly visible. If it were under the seat, there's no reason the cop should find it. Again, he's not allowed to illegally search, so he can't look under the seat even though he's temporarily seized you and your car to investigate the suspected traffic infraction.. In the same way, he's disarmed you legally, but only to prevent the weapon from being used against him, not because the weapon is part of his investigation or suspected evidence. In that way, he should not be permitted to search it.
To go one step further, what if I'm wearing a paddle holster, and after explaining he will be disarming me for his safety, I suggest he simply remove the entire holster. It not only satisfies the reason he is allowed to disarm me in the first place, but also maintains a secure state of the weapon by also eliminating (most of) the risks of handling an unknown weapon. Would he still be justified in unholstering the pistol and clearing it? I of course understand not everyone wears paddle holsters, just a thought...
Notwithstanding anything I just said, utbagpiper raises a very interesting question - in the process of clearing the weapon, despite my objection, would any discovered incriminating evidence be admissable?
And since you're never wrong if you stand on both sides of the fence, I'll go ahead and do just that. :-) An officer may not search your shed without a warrant...but if he's in the process of chasing a bad guy who decides to hide in your shed, the officer does not need a warrant to enter the shed to capture him. If he discovers a stash of pot, he may collect it as evidence and possibly charge the shed owner with possession. An obvious defense would be that the bad guy, nearing capture, ditched the stash to try and avoid compounded charges, but the warrantless search is still legal.
I just wish it were clearer. It's hard enough to try to understand all the laws you're expected to obey, especially considering "ignorance is no excuse", but when you make an effort to understand as many laws as possible, and the language is ambiguous or open to interpretation, how can ANYONE be sure they're not breaking any laws?