How we change what others think, feel, believe and do
Refuse to give in on items based on the fact that you have not been given authority to do what is being requested by the other person.
You can, if you wish, offer to take the request back to that authority for consideration (and, at the next meeting, tell them that the request has been turned down).
You can name the authority, particularly if the person named is known and has a high position.
Sorry, I only have the authority to spend up to a thousand.
I'll have to ask your mother about that.
I'd love to give you that, but I don't think I'd get away with it.
When you claim that you do not have authority to make a decision, then this effectively prevents the other person from disputing your decision, as the authority person is not there.
If you use the name of a person in particularly high authority, then you gain by proxy a certain amount of that authority, and can make more demands than you might otherwise.
Claiming no authority can cause problems when the other person asks to deal with the person in authority. For this, you will have to be able say no (you do have authority for this!).