It is definitely best to get your license back before your court date, which will almost certainly require paying your fines in Idaho and getting reinstated there. There are ususally possible positive outcomes for a DWLS 3 charge, often including an amendment to a non-criminal traffic infraction NVOL charge, so be sure to consult an attorney on this...I and others would be happy to discuss it with you further.
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If you have an Idaho driver license, you need to take care of the unpaid ticket in Idaho and reinstate your license in Idaho before you will be recognized to drive in Washington. The ticket in Idaho is separate from the criminal charge in Washington and must be addressed separately. DWLS 3 is a criminal charge in Washington so there is every reason to be concerned because jail time is possible with a criminal charge. Paying off the ticket in Idaho and getting your license reinstated is a good start before the next court date in Washington.
You will need to take care of the ticket in Idaho, it will not be transferred here. You are on the right track. Getting you license back prior to the hearing will help immensely, and depending on your criminal history, you may even be able to get the DWLS dismissed if you show a valid license.