The bill would also make it illegal for employers to make it a condition of your continued employment.
Employers shouldn't be checking up on their workers during their personal time, according to the bill's sponsor, Sen. Steve Hobbs, D-Lake Stevens.
"This is a good idea to do this now, nip it in the bud," said Hobbs.
The bill is currently in a Senate committee. Violators would have to pay employees $500.
Legal experts say gaining access to someone's Facebook or other social media accounts could reveal chronic health conditions, disability, pregnancy, faith, political views, or sexual orientation, which employers are generally not allowed to ask about.
But some say social media has blurred the line between personal and professional aspects of one's life.
"You might actually hire someone for their existing following and use their connections for your business. At what point does that fall into
this bill? It's a gray area," said Michael Shaw of the Washington State Bar Association.
And what about gaining access to your activities or habits? Employers in Illinois have been sued for discriminating against applicants and employees for their use of lawful products, like cigarettes or alcohol.
Maryland is the only state so far that bans employers from asking applicants for their social media log-ins. But whatever an employer finds out there in the public domain is fair game.