If your BAC is in excess of 0.08 grams, you can be charged with driving while intoxicated (DWI) in Washington, DC. A DWI means that the government has to prove your BAC in court. They do not need to show that you were actually impaired. However, this may not be as easy it sounds given the many problems DC police have had with their breath testing program. If they cannot prove a specific BAC, or your score was less than 0.08, they can charge you with driving under the influence (DUI) which requires proof of being under the influence of alcohol.
If your DUI lawyer is familiar with breathalyzer equipment, and field sobriety testing, there may be a lot that can be done to help your situation. It is important to remember that an arrest for a DUI is not a conviction.