​May a legislator wear/display their legislative badges paid for with public resources at a campaign event?

​No. RCW 42.52.180 prohibits the direct or indirect use of public resources to campaign.  There is no de minimis exception for use of public resources in a campaign. Ruling applied prospectively.  Badge also contained the State Seal and that issue will be forwarded to the Secretary of State who enforces the prohibition against campaigning with the use of the Seal.