If you are talking about a residential rental, the Residential Landlord-Tenant Act is at http://apps.leg.wa.gov/RCW/default.aspx?cite=59.18 . Your city or county may have its own residential laws.
Interestingly, the RLTA does not appear to specifically require a joint walk through at any time during the rental. RCW 59.18.260 requires a written checklist documenting the condition of the premises at the beginning of the rental and signed by both the landlord and the tenant when the landlord requires the tenant to pay a deposit. Since the checklist can be made by the landlord and tenant separately inspecting the premises, the landlord likely does not need to do a walk through with the tenant.
The RLTA does not appear to have a provision for a walk through at the end of the rental.
If the landlord claims damages, the landlord would have to have proofs to support the claims. If the tenant claims a lack of damages, the tenant would have to have proofs to support the tenant's claims. They each likely should videotape, take pictures, or have third parties inspect the premises.
You likely should review your facts and options with an attorney.
If you paid a deposit then the landlord must, among other requirements, give an accounting to you within 14 days of your leaving the property and a written checklist "specifically describing the condition and cleanliness of or existing damages to the premises and furnishings, including, but not limited to, walls, floors, countertops, carpets, drapes, furniture, and appliances, is provided by the landlord to the tenant at the commencement of the tenancy." RCW 59.18.260.