It depends. I don't practice in AZ, but in most jurisdictions the police must see you driving to arrest you for drunk driving. It is certainly worth fighting.
If you request a public defender, the court will evaluate you financially to see if you qualify.
Edward J. Blum
You may have some valid defenses. First, how could you be driving or in control of the vehicle when you were sleeping? Where was the driving/operating? In WI, we have caselaw indicating that sitting behind the wheel of a parked, running vehicle without more is not operating. For operating, the person must physically manipulate a control necessary to put the vehicle in motion. AZ may have similar case law.
There is also the shelter doctrine. Under this doctrine, you would argue it was necessary for you to sleep in a parked, running vehicle. Usually, this applies to cases in States with snow, but maybe there is a way to get this doctrine to apply in your case. Maybe air conditioning is a must have in AZ!?
Bottom line: You may have valid defenses. You should definitely get a court-appointed attorney to assist you.
As for what to expect in court, you will need to discuss that with your attorney.
I am an Arizona licensed attorney with experience defending DUI cases.
In Arizona, the State must prove that you were driving, or "in actual physical control," of the vehicle. Pursuant to case law, various factors (i.e., key in the ignition, hood of the car warm to the touch, your position in the car [behind the wheel vs. in the back seat], your statements regarding driving, etc.) can be used by the State to show that you were in "actual physical control" of the vehicle.
With that being said, these types of "actual physical control" cases are often easier to defend than cases where the officer observed the person driving.
If you do not hire an attorney, expect to be in Court most of the morning or afternoon filling out forms to determine whether you can afford an attorney or not. Arizona statutes require mandatory jail time if you are convicted of a DUI, so you will be appointed a public defender if you cannot afford an attorney.
There is a resent case form the Arizona that addresses physical control and the factors a jury should consider. I wrote a post on it from a Washington DUI Attorney's perspective, but it may have some helpful information for you.
I am a DUI lawyer practicing in Jacksonville, Florida. Like Arizona, Florida requires the State to prove that the defendant was in actual physical control of the vehicle. However, I have experienced cases where a person was arrested for having the car keys in the ignition while sleeping on the side of the road and the Court ruled that the defendant had the intent to drive the vehicle as his keys were in the ignition. I suggest you obtain an attorney to help you argue your side. In most cases, the State will not simply drop your case without you setting forth a valid legal argument for them to do so. Get an Attorney!
It depends on the specific facts. Was the car running, keys in the ignition, car in gear? Was your foot on the break?
Deteremining the operarting element is very fact specific but it coudl go your way depening on all the factors.
You should do some research or acquire counsel to help. Most states, have another DUI statute to the usual DUI ... (driving, over the limit), one that essentially says that law enforcement doesn't have to prove that you were driving, but were just in actual "physical control." But there may be some type of defense right there in the statute that it may be a defense to DUI if you can show that you "were safely off the roadway" or something similar to that language. Washington State has a statute like that, RCW 46.61.504... You're state may have the same. Good Luck.