Can you become a US Postal Inspector if you have used marijuana for more than three times?

How is your employer going to know when and how much marijuana you have smoked in your past? I think the real concern is whether you are smoking now, while employed. Many employers believe that people who smoke marijuana are a liability, prone to illness, more sick days, lower productivity, greater risk for accident and injury, so they will urine-test before and during employment. A positive urine test can cost you your job in many places.