The law of client/attorney privilege and the Constitutional prohibitions against unreasonable search have distinct bases and are governed by different law. Attorney/client communication focuses on the whole communication, while 4th amendment focuses on the specific piece of evidence. So if you for example gave your client some advice relayed through your secretaries, you could invoke the privilege if they were questioned. However, if you gave your secretary a note to pass to your client, and she kept a copy, you cannot invoke the 4th amendment.

What if I FedEx a letter and a FedEx employee opens it and keeps a copy of it? (Replace FedEx with USPS if it makes a difference)

There is no reasonable expectation of privacy when it comes to private carriers like FedEx or UPS. The expectation of privacy only extends to First Class USPS mail, under the consideration that extra protections are needed given that the USPS is an organ of the federal government and that USPS workers are bound by the 4th amendment just as any other agent of the government (and unlike private mail carriers!)

> There is no reasonable expectation of privacy when it comes to private carriers like FedEx or UPS.

Absent an expectation of privacy, the government is entitled to search whatever and whenever it pleases. Are you suggesting there is court precedent establishing the government does not require a warrant to search a box being delivered by UPS?

With UPS' consent, I'd guess.

That is your own speculation, not established precedent, and I would argue UPS is now acting as an agent of the government anyway.

So, again, what actual precedent exists to support rayiner's contention?

I agree. If you sign an agreement with UPS that allows it to simply give your package to the government upon its request, then you've effectively waived your Fourth Amendment rights.

But, absent that, the government cannot simply compel UPS to hand over the package or relay its contents without a warrant. That would be a violation of the Fourth.

OTOH, if the UPS employee simply looked in the box, it wouldn't be a Fourth issue. It is only so if the employee did so at the behest of the government. In other words, you are correct: in that case the employee is acting as a government agent[1], which triggers the Fourth:

[1] http://www.fletc.gov/training/programs/legal-division/podcas...

Edit: Key clause:

Miller: Can private parties ever trigger the 4th Amendment?

Solari: Yes, as we discussed, if a private party were to be acting at the behest of the government -- if a government agent were to ask that FedEx person to open up a package and look inside, or to ask someone’s girlfriend to go through their things looking for evidence to turn over to the police, then that would be government activity. That would be the actions of a government agent because government agents can’t ask private parties to do something they themselves couldn’t do under the 4th Amendment, so in that type of instance it would be extended to that private party.

Thank you. I didn't know of this distinction. I poked around a little and found something at the EFF website[1].

Now my next question is can someone force the third party to give up the information without a warrant? I know they most likely will just comply. However, just for completeness, can a company like FedEx say that they require a warrant before opening packages?

[1] https://ssd.eff.org/your-computer/govt/privacy