Just because you sign a consent form at admittance does not remove your legal right to informed consent and informed refusal. A provider has the legal obligation to give information on the risks and benefits of each drug and procedure they are introducing and make sure you consent each time they perform a procedure.
Here is a way of talking with a provider (doctor or midwife or nurse) about your all of your options during labor, to help you make an informed decision. It is an acronym: BRAND.
B – What are the Benefits of this test, procedure, intervention?
R – What are the Risks of this test, procedure, intervention?
A – What are the Alternatives to this test, procedure, intervention?
N – What if I do Nothing?
D – Based on the information gathered, we make a Decision.
http://myhealthfreedom.com/index.php?id=172 (Applies not only to VBAC's, but all births and is federal law!)
http://birthways.org/category/tips-from-a-midwife (Tips on talking to your provider.)