If you're pulled over for Driving Under the Influence (DUI) of alcohol or drugs in Spokane County or anywhere in Washington State, then the officer will likely ask you to perform roadside tests called Standardized Field Sobriety Tests (SFST's). These include a test of your eyes (Horizontal Gaze Nystagmus or HGN), and two agility tests like walking heel to toe (Walk and Turn or W+T) and balancing on one leg (One Leg Stand or OLS). You may also be asked to blow into a handheld breath alcohol test called a Portable or Preliminary Breath Test (PBT). The Washington State Patrol website has many DUI training manuals including a recent manual regarding FST's.
Law enforcement officers in Washington State are required to tell you these tests are voluntary. However, after reviewing hundreds of dash cam videos from DUI stops, this advisement that the tests are voluntary most often sounds like a command: "Would you like to perform some voluntary field sobriety tests so I can make sure you're ok to drive?" The voluntary part of that statement often gets lost in the panic of the accusation that you have to prove your sobriety.
In most circumstances, you're better off politely refusing all roadside tests. The roadside agility tests are awkward and unnatural movements. They have more in common with Olympic gymnastic events than driving a car. Most people - even those who have consumed no alcohol or drugs - will not perform these tests perfectly. Therefore, your performance on the roadside tests usually won't help prove sobriety, but will instead be used against you as evidence of intoxication. Again, most people are better off politely refusing these roadside tests.
General advice can be helpful. However, if you stand accused, then you should immediately consult with a Spokane DUI attorney to get advice specific to your case. Time can be of the essence as most DUI's in Washington State have two separate cases with short deadlines.