Can you take a vow of silence that is legally binding?

There are two ways of looking at your question - Can a vow of silence be enforced by whoever you made the vow to, and can you use your vow of silence to avoid speaking to government agencies.

1. Vows made to religious orders are between you and the church. If you break it, it simply means that you no longer can insist on whatever priviliges or position the church was giving you.

If you actually agreed to remain silent in exchange for something, such as a fee, and the fee was given to you up front, then they would have civil recourse to sue you for the return of the fee they paid. Room and board, or even salary, would not count as a fee up front, or payment to be refunded. That would have only been payment for your time in, not a fee for a lifetime of silence, or even so much as one day more of it.

(A confidentiality or non-disclosure agreement is a separate matter, and can have civil penalties - or criminal - for breaking it.)

2. Vows of silence that you took in your church - or for any other reason - have no recognition in law. That is to say, you have the exact same rights to speak or not to speak that you would have had if you hadn't take such a vow.

The right not to speak is not so broad as those who rely on "Law and Order" for their legal training would have you believe. The only way to reliably remain silent with the police is to never talk to them at all, beyond either stating your name, or better, simply providing your ID. Doing otherwise can in some cases be taken as a waiver of your rights against self-incrimination that you later cannot legally reclaim. (Raffel v United States)

While the Fifth Amendment lets you remain silent (assuming you refused from the very start to not speak with police), it can be breached by the State if they give you immunity, such as for purposes of a Grand Jury inquiry. You may be held in contempt of court if you do not speak after the immunity is granted.

Press shield laws are not absolute. Attorney/client privilege - as well as doctor/patient and clergy/parishioner - are not absolute. Gun shot wounds, child abuse and such, can be grounds for compelling violation.

Not examined by the Supreme Court yet is the last hope for a "legally binding" refusal to speak. That's invoking not the fifth amendment, but the first. In legal theory, all constitutional rights assume their opposite - a right to bear arms means a right not to bear them, a right to practice religion means a right not to, etc.

One could argue - at one's own legal expense and potential peril

• that they are invoking a First Amendment "right not to speak",

and if they wished, cite a "vow of silence". (Presumably their attorney would have to explain all that for them.) However, the Supreme Court has always regarded "not speaking" as needing to be balanced with "state interests", just as they do "speaking".

In other Words, while they've not explicity denied a first amendment "right not to speak", you probably have lost before beginning.

Conclusion:

The long and short of points one and two is that you cannot be made to keep a vow of silence unless you were paid in advance to do so for a set period. Breaking it would then be a civil, not criminal, matter.

And you cannot invoke a "vow of silence" to avoid speaking to the government, except for if you simply refuse to talk to the police at all in an investigation, and never at any point break this till any trial is over. (One must still show that ID, or state their name) And that can be broke by a grant of immunity.