The rules governing Administrative License Suspension hearings are laid out in WAC 308-103, to which a link has been provided for your convenience.  These administrative hearings consist of a phone hearing at which you will be represented by your DUI lawyer and the DOL by an assigned hearing officer.  You will have the right to testify, present witnesses, present evidence and even to subpoena the arresting officer if you or your attorney so choose.  Unlike criminal cases, the DOL only has to prove its issues by a preponderance of the evidence.  The issues to be decided are found on your hearing request form and are as follows:

1. Whether you were under lawful arrest.
2. Whether an officer had reasonable grounds to believe you had been driving or were in actual physical control of a motor vehicle within this state while under the influence of intoxicating liquor or any drug, or whether an officer had reasonable grounds to believe you had been driving or were in actual physical control of a motor vehicle within this state while having alcohol in you system of 0.02 or more and were under the age of twenty-one.
3. Whether you were advised of your rights and warnings as required by RCW 46.20.308(2).
4. Whether you refused to submit to the test, or if the test was administered, whether the test indicated an alcohol concentration of 0.08 or more if you were age twenty-one or over, or 0.02 or more if you were under twenty-one.

The rules governing these hearings give broad discretion to the Hearing Officer, who not only acts as the arbiter of the case, but often times the prosecutor as well. Realistically, in order to prevail in this environment, you will need to have an experienced DUI attorney who is familiar with the Washington DOL, it's hearing officers, and this forum.