King County Sheriff John Urquhart is in Washington D.C. to testify at a Senate hearing about the state's marijuana law.
Senators want to look at the conflict between state and federal pot laws. The hearing starts at 11 a.m. PDT.
This is the first congressional hearing since the justice department gave Washington and Colorado the green light to implement their pot legalization laws.
Urquhart supports the law. He wants Congress to change federal banking regulations so marijuana stores can open checking accounts and take credit card payments.
"The reason I want to make sure these banking laws get changed, these are going to be cash only business, doing a lot of business most likely," said Sheriff Urquhart. "Anytime you have a cash only, I have to respond to robberies, my deputies have to respond to armed robberies."
Currently, these businesses can only accept cash.
Governor Jay Inslee and Attorney General Bob Ferguson also want Congress to fix the banking rules or at least let the banks know they won't be prosecuted federally for taking money from state-licensed marijuana businesses.
Inslee and Ferguson sent a letter to the judiciary committee.
After Tuesday's hearing the medical marijuana advocacy group Americans for Safe Access will host a Google hangout to discuss reaction to the testimony. The public is invited to join the 2 p.m. hangout.