This would mean that if it were customs, it would be preclearance for Mexican customs at FAT, correct?

Considering what TSA has been done in Newark and Hawaii why would you be surprised?

Does customs generally get involved in resolving security alarms on outbound international flights?

In my opinion, TSA is NOT within their rights to use a NoS, or any form of visual / imaging inspection underneath clothing. They assert they are within their powers to do both.

Underlining mine to indicate the question that nco4242 is replying to. There is the potential here that the screeners examined the photos in the camera, which is clearly outside their authority to screen only for W/E/I.

PLEASE submit a complaint to DHS, TSA, your Senators and Representative, ACLU, EPIC, etc!

Why is the TSA snooping through passengers' cameras?

If there was ever a YouTube moment-in-the-making, they were about to have one.

Good post - similar AUX and P/T police officers who wear a police uniform and possibly even drive a CVPI... with the only difference being AUX marked somewhere on the car and AUX appearing somewhere on a patch...when a member of the public sees the uniform and the car...and they need assistance, they don't distinguish, they just go to them for help. The problem is many AUX officers are not allowed to carry. I can see how that could happen between CBP and TSA. It is possible that there is confusion here.

If it powers up, it's a camera, not a bomb disguised to look like a camera. That would be the security premise for turning on a camera/laptop/other electronic device.

You misunderstand the nature of oral arguments in an appeals court. The questions are very often (as in this case) hypotheticals meant to explore the boundaries of what the advocate perceives to be the law. There's been no posted transcript of the hearing, but knowing the way these arguments work, I'm almost certain you are misinterpreting what was said.

The way I understand the exchange, the court was trying to address the issue of regulatory authority, whether TSA needs to have a formal regulatory process or can just make a change in checkpoint procedures without such a process. TSA was claiming the latter. To explore the boundaries of that, the court asked a question, specifying what everybody understood would be an unacceptable procedure. The TSA's answer was that was no matter what the procedure, they didn't need to go through a formal regulatory process. The discussion there was about the process of changing the procedure, not the acceptability of specific procedures, and indeed the US attorney said that such a procedure would have 4th Amendment issues.

Or so they'd have us believe. Real security personnel make the person carrying it turn it on, not remove the device from the person and take it somewhere else to turn it on.

If they really thought it might be a bomb, why are they playing with it?

The OP stated this was when being screened for departure at FAT. Since you don't clear customs when departing the US on an international flight, I think it's safe to say with 100% certainty that these actions were performed by TSA smurfs.

Bolding mine: Naughty, you! Using the S-word! Mods swooping down on your post in 5....4....3....2...

Excellent point! What if turning if turning it on resulted in a detonation...oh, never mind....wishful thinking again! </sarcasm>

Correct. Overseas I have been asked to power up devices by foreign security screeners on a number of occasions. In every case they asked me to power up my device, visually verified it powered up and then asked me to turn it off.

Nice change of terms Bart. At first you called the OP a liar and said they were never strip-searched, now you claimed they were never strip-searched "by the TSA". Way to go.