Using cash to buy something secondhand in Louisiana? Nope, not legal. The State Representative who co-authored this particular bill stated, “They can give a check or a cashier's money order, or electronic transfer." This may have been in order to keep people safe buying things off say, craigslist. But it's also a good way to may sure there's a record somewhere of any transactions done outside of a store, so that's creepy and invasive.