TL;DR A person can face both state and federal charges for the same act when that act violates both state law and federal law. Double jeopardy prevents repeated prosecutions by the same sovereign, but states and the federal government are treated as separate sovereigns. The dual sovereignty doctrine allows state and federal governments to prosecute …
Being arrested for a crime does not necessarily mean you will be convicted. Often we can help you get charges reduced or dismissed, and avoid jail and a criminal record.