employee vs independent contractor

State: California

is someone who works inside an office and uses office equipment always considered an employee? What if they have willfully signed a W-9 & I-9? Is there anything which eliminates their eligibility for employee status? (assuming no independent contractor agreement exists.)

thank you for your help!!

Not in and of itself.
http://www.irs.gov/govt/tribes/article/0,,id=134976,00.html