Always KNOCK on a closed door.

Typically, doors are closed for a reason.  

Privacy.  Confidentiality.  Noise.  Keeping you – and whatever is on the outside of it – OUT.  Think of your boss’ door.  A bedroom door.  A public bathroom door.

You wouldn’t just open the front door to someone’s house, right?  Proper “life etiquette” tells us to knock first.  Why should any other closed door be any different?

Never assume the lock works.

Ever have someone walk in on you in a public bathroom?  Of course you would have locked the door before conducting your bathroom business if the door’s lock was in working order, right?

It only takes ONE time as either the bathroom goer or the “non-knocker” to learn that you should always knock on a public bathroom door.  Pretty embarrassing for both of you, right?  Certainly, the most valuable lesson is learned by the non-knocker.

Knock.  Listen.  Crack.  Proceed.

Take my advice.  KNOCK (hard).  Press your ear against the (usually heavy) door and LISTEN for a response.  If there is no response, keep assuming someone is beyond the barrier and that they are just so caught up in their transaction to hear your deliberate knocking.  CRACK the door.  Give the potential party on the other side one last chance to declare occupancy. PROCEED.

And next time you’re in a public bathroom and a non-knocker jiggles that door handle as if they’re trying to break and enter, you can say politely as you exit – “Whew, good thing that lock works.”

Assuming the lock worked.