Unless a consumer chooses to opt-in for overdraft protection, their ATM and debit purchases will be declined if an account has insufficient funds.
My bank tried like hell to corral us into an overdraft protection plan. There must have been a half-dozen letters begging us to opt-in. Sorry, no. We don't skim the bottom very often, but I'm satisfied to endure the embarrassment at the register if it happens from now on. The couple of times recently when it happened (there was a recession on!), we didn't know about it for a couple of days until there were multiple penalties on the account.
By the way, my bank took $300,000,000 in TARP funds. Glad to see it spent some of its money on multiple letters hectoring us about overdraft protection.