Originally Posted by
fastair
Since this question popped up again, my advice to get a fair answer is to ask a customs agent if he/she thinks it is acceptable. After all, it is their process that you would be short circuiting. It isn't the airlines that want to spend the extra resources of manpower, time, and equipment to unload bags, deliver them to the belt, then pick them up again to send them back to the TSA and a sorter system. I'm sure the airlines would much rather skip this process altogether, but because of Customs regulations, they must do this. So the question really is, "Is it OK to not follow CBP's processes and do what is convenient for me?" To get an answer to that, ask CBP. I'd be willing to bet my next raise (it's a big one) that their official answer is "no."
Ask the customs agents, yes, but they understand the bigger picture in my experience. Moreover, it is not as though they are losing the ability to scan/search any bag they want if they give you express permission to move through screening without your bag.
Case in point: we flew DEN-YYZ-YUL-CDG last year and as such needed to claim bags in YYZ to make the domestic connection to YUL. Bags didn't show up and all we were getting was a lot of nonesense from the AC folks in the baggage hall. After about 45 min, and at the point our connection began to get risky, I simply went up to customs agent, told him what was going on, and he immediately understood and ushered us through to fill out a quick form and be on our way. This was of course Canadian, not US, law enforcement, but I imagine US agents would react generally the same way so long as your story makes sense, it does in fact appear you are running late, and your bag can't be found (i.e. there is no reason to be suspicious that you've had a change of heart about carrying your bag through CPB screening or that you merely prefer the LH lounge to the portable classroom-like C/D gates lounges and need the time to get over to B).