Citigroup can limit demand deposit withdrawals and money funds can too

"This may be good for Citi but I wonder how it is legal. After all, the point of a demand deposit is to provide safekeeping for one’s money. Otherwise, with interest rates at zero percent, why not just keep your money under a mattress? I find it hard to believe that Citi can simply decide to require seven days notice. I am sure that Citi uses the standard credit card tactic of issuing all affected account holders a notice in full legalese of the changes that are being instituted, giving them an option of closing their account."