DUI, CONTROLLED SUBSTANCE CHARGE IN ALABAMA

The fact that he was sleeping at the time does not necessarily negate the charge of DUI.  "Driving" or "operating a vehicle" is typically defined as the ability to exert control over the vehicle. Officers usually need not observe someone driving in order to arrest them for drunk driving. Circumstantial evidence of driving is typically sufficient to establish this element.

Here, the keys were in the ignition and your brother was behind the wheel. Clearly, at any time he could have exerted control over his car.  Additionally, the fact that he was drunk and/or a controlled substance was found could be considered to be circumstantial evidence that he drove home while under the influence.  While these allegations can be refuted in court, the charge can still be made.  Whether or not a conviction is obtained is another matter.

Since these can be tricky cases, your best bet is to have your brother consult with an experienced DUI attorney.  Possibly the charge can be dismissed on a technicality or at least reduced.

Best of luck.