To start the process, you have to prepare a summons and complaint and file both documents with the Court.
1. The Summons
The summons provides written notice to the Court and the opposing party (i.e. defendant) that you have filed a personal injury lawsuit in Washington. The most important part of the summons tells the defendant that he or she has to formally respond to the lawsuit within 20 days or else the plaintiff can seek a default judgment.
Unlike the complaint, the summons doesn't include any specific information or facts about your case, other than the names of the parties and the name of the Court.
The law requires that a summons have standard, boilerplate information, so feel free to use my template as a guide. No need to re-create the wheel.
2. The Complaint
The complaint actually describes your lawsuit. You tell the Court what happened—when and where the injury took place, the injuries you suffered, and your interactions with the defendant. You also describe your damages, such as lost wages, emotional distress, pain and suffering, repayment of medical bills.
3. Filing Your Documents
After you prepare these two documents, you must file them with the Court. Technically, you can file them separately, but you should always file them together.
As with everything in life, it costs money to file a lawsuit. To file a lawsuit in superior court, you have to pay a $220 filing fee. To file in district court, it only costs $83.
You may be able to file your lawsuit online. In King County Superior Court, for example, you can easily file online using the Court's E-Filing service. You simply register for an account, answer some basic information, and you're done. There's no additional filing fee. Attorneys are required to e-file documents, but it's optional for pro se (i.e. un-represented parties). You can also file online in Pierce County.
In many counties, however, e-filing is not an option. Snohomish County and Whatcom County require that you file by mail. San Juan County permits you to file by fax, but using that option requires an additional fee.