Independent contractors: Can we examine their costs, or would that undo their IC status?

Q. We are a not-for-profit business league. We use an independent contractor for most of our government affairs programs. The IC has his own employees. The contract cost is around one-third of our entire annual budget. Many of our volunteers want to know where all this money goes. My boss tells committee members that they (and we) have no right to know the details because he's an independent contractor. I don't agree with this. My boss says us having these details and being able to account for the $1 million in expenses will undo the IC status. Is this true? – Becky, Nevada