[yaur]

If you have a general policy where you have to talk to their direct manager or where you always have to talk to the CEO then you might be alright. But if you are making a special policy for employees of a certain company you should probably be talking to a lawyer first. This kind of stuff is almost all state law, so there isn't going to be a universal answer.

That aside, in the scenario "Fred" is good friends with one of your top engineers in the scenario presented. If you ask "Cathy" and she says yes everything is golden, if she says no and Fred gets canned or Cathy's company goes under one of your top employee's good friends is now unemployed because you put your personal relationships ahead of the buisness. This is not a good situation to be in.

Also from the article: "It is important to note that just about all of these kinds of policies violate the Right to Work laws in California"