False DUI and overspeeding charges.

They pulled me over and arrested me on charges that I did not do, for overspeeding and drunken driving, and seized my car. They released me after two days in custody and did not file any charges against me. I was informed that my licensed has been revoked and my car will be with them for 30 days. Isn’t it necessary for them to have a valid reason for doing these things to me? I was never involved in any kind of brawl with the administration, except for this. How do I get out of this mess? I am from Middleton, Idaho.