Can you use an ATM card at an ATM without knowing the pin?

That depends on what you're using it for. If you're using it to obtain money from an account, or any other form of account access, it will not work. However, if you're using it as a bookmark, it will work just fine. You could also use it as a toothpick, a scraper, a putty knife, or as a ramp for a finger skateboard. However, you can do all of these things at some place other than an ATM, and the people waiting in line behind you would really appreciate it if you got out of their way so they could use the ATM, and their own ATM cards for the legitimatepurpose of withdrawing money from their own accounts. On second thought, there is one way you could use the stolen ATM card in your possession to obtain money from its actual owner's account. What you do is, you locate the nearest police officer and tell him that you stole this ATM card from someone, and would like his help in using it to access someone else's money. The police officer will be glad to help you out. Before he does, though, he will likely read you a series of statements about rights and attorneys and remaining silent and all that, then he'll ask if you "understand these rights". Say yes, then tell him again that you stole the ATM card and would like his help in using it to access someone else's money. The police officer will take care of you.