You may hear stories of people being detained for drunk driving after registering a blood-alcohol measurement in excess of the legal limit and wonder why anyone in Covington who might potentially be driving drunk would consent to such testing. This likely comes from your assumption that law enforcement officers cannot force you to do anything that you do not want to do. What you likely do not know is that you (and every other driver in Kentucky) has already agreed to such testing.
If you are wondering when you made this agreement, understand that the state has enacted an "implied consent law" (whose details can be found in Section 189A.103 of Kentucky's Revised Statutes). According to this law, by operating a vehicle on any of the state's roads, you have consented to have your blood, breath or urine tested for any substance that may impair your driving ability. A refusal to submit to such testing could result in criminal penalties independent of those you may be charged with if authorities believe you were driving while intoxicated.
Interestingly, field sobriety tests and preliminary alcohol screenings (roadside breath tests administered with a breathalyzer device) may not fall under the purview of the state's implied consent law. You can, then, refuse such tests. However, doing so may provide an officer with probable cause to believe you are intoxicated, at which point he or she can subject you to the chemical testing mandated by the law.
After you have completed any of the tests required by law enforcement, you are then entitled to have your own round of testing done by a person of your choosing. If the results of subsequent tests refute those done by law enforcement, you might be able to use them to challenge any charges filed against you.