2023 Washington Code 80.28.090 – Unreasonable preference prohibited

2022 Washington Code 80.28.090 – Unreasonable preference prohibited

2020 Washington Code 80.28.090 – Unreasonable preference prohibited

2019 Washington Code 80.28.090

2018 Washington Code 80.28.090 – Unreasonable preference prohibited

2016 Washington Code 80.28.090 – Unreasonable preference prohibited

2015 Washington Code 80.28.090 – Unreasonable preference prohibited

2014 Washington Code 80.28.090 – Unreasonable preference prohibited

2013 Washington Code 80.28.090 – Unreasonable preference prohibited

2009 Washington Code 80.28.090 – Unreasonable preference prohibited