Perhaps I shouldn't have included the caveat about legal advice in my answer to the question 'Provider is “cheating”, but I don't want to disclose how I found out'. Here's the paragaph in question:
We don't normally provide legal advice here, and you should definitely know that I am not a lawyer and this shouldn't be construed as legal advice. That said, if a law suit were to develop over this, you might need that junior programmer as a witness. However, as an employee of the provider, the programmer may not repeat in court what they told you. You might investigate hiring him or her yourself, or having your client hire them; of course, if that were to happen, the other side would try to impugn the testimony of someone who is now your (or your client's) employee.
IMO, my last paragraph isn't really the kind of legal advice one would get from an attorney, just some "street smarts" for going to trial, as well as an idea about protecting the source. However, it is attracting comments complaining that it's legal advice and thus off topic. If the consensus of the community is that this goes outside the scope of the site, I'll delete the paragraph.
Update: That paragraph was modified to read:
If you really want to protect the junior programmer and have a slot he could fill, you could hire him yourself, or your client could hire him. This way he's sure to avoid being fired by the service provider. Also, in case the service provider tries to sue your client for breach of contract, you're sure to have him around as a witness.