It's the same notion that compels people to write "I don't own this song" under the youtube uploads of albums, as if mentioning copyright issues absolves you from them.

That being said, there are magic words that you can say that have very strong legal weight. For example, attaching a GPL licence to a piece of code you wrote has significant legal ramifications.

It's clear that "Under penalty of perjury" doesn't accomplish the intention of giving a canary message greater legal weight. I am, however, curious if there are some other "magic words" that could exist in a canary message which would help to signify its validity. For example, making it illegal for someone to fake the canary message.

I actually don't know if the government could require you to falsely affirm the nonexistence of a legal investigation as part of a gag order - in other words, if you simply stopped publishing your canary message, whether you could be required to do so. Perhaps the failure to comply with such a request would qualify as an obstruction of justice if therre were a colorable risk of it impeding a lawful investigation by tipping off the subject of the investigation; law enforcement officers with an appropriate warrant or authority could require an explanation of how the canary mechanism worked, in the same way that they could require you hand over keys to one's safe, say. There's no right to silence for non-defendants such as material witnesses.

First, thanks for adding good insights into what would (and would not) stand in court.

Would a 5th Amendment right (not witnessing against herself / self-incrimination) protect the owner of the ISP against a charge of obstruction of justice?

i.e. Owner of ISP refuses to post the canary after a gag order. She is not named as a defendant in the investigation. But she can defend herself against obstruction of justice charges: plead the 5th, and thus she is not compelled to falsely affirm the canary.

It's not clear this would work, either, but there might be some pretty solid precedents that could be used in this way.

A sworn affidavit is made under penalty of perjury.

http://en.wikipedia.org/wiki/Affidavit

A bit more administrative hassle, but the concept should be sound.

A sworn affidavit has to be given to someone legally authorized to take it, which is 'anigbrowl's point.

Wikipedia refutes your argument:

http://en.wikipedia.org/wiki/Perjury

The rules for perjury [apply] even if the person has not been sworn or affirmed as a witness before an appropriate official.

Also relevant:

http://en.wikipedia.org/wiki/Subornation_of_perjury

Subornation of perjury is the crime of persuading a person to commit perjury; and also describes the circumstance wherein an attorney causes or allows another party to lie.

It's pretty clear this, not magic, is the end goal of the original statement.

You've misunderstood the Wikipedia article, which is not surprising because it is poorly written. The government can establish mechanisms for people to provide statements "under penalty of perjury", such as IRS forms. But the mere words "under penalty of perjury" aren't a magic incantation; they have force only when specifically given it by the government.

"Under penalty of perjury" is just a mechanism for substituting a written declaration for an in-person swearing.

If you look at the statute, the governing condition is (paraphrased) "under laws or circumstances requiring or permitting a sworn statement".

IANAL, but 'anigbrowl has some training here.