You can be arrested for a DUI even if you are not driving at the time. The fact is, the police do not have to actually observe you behind the wheel of a moving vehicle. Under the law all that is needed is evidence of driving. And the officer indicated that they saw you get out of the driver's side of the car. This would have been legally sufficient to demonstrate that you exerted control over the car. Additionally, the tests administered to you at the scene (breathalyzer and field sobriety) legally established that you not only exerted control over your car but did so at a time when you were intoxicated. Why you were stopped in the first place is not clear but obviously the officer had reasonable suspicions for doing so; you may have smelled of alcohol, were acting in an inebriated manner, etc. Bottom line, you were over the limit.  That having been said, this doesn't mean that you don't have legal grounds on which to fight the charge. Defenses can be enlisted which could result in getting the charge reduced or dismissed. You realy should consult with a DUI attorney in the area where you must make your court appearance. They will have contacts within the local court that may be able utilized to your advantage. Since a DUI triggers both civil and criminal cases, retaining legal representation is highly advised.