What is the burden of proving privacy in a search warrant?

The majority opinion today and the district judge below places on Mackey the burden of showing he had a reasonable expectation of privacy in the bag and so deserved the warrant safeguard. But the burden should have been on the government. Here the government barely presented any justification for excepting this search from the warrant requirement, let alone carried its burden. It merely argued that Arkansas v. Sanders applies only to luggage. As even the majority states, that argument is incorrect. If this is to be a new exception, the government presented neither evidence nor argument about what compelling societal reasons justify this new exception. The applicability of other existing exceptions is doubtful. Mackey and his co-defendant had been arrested before the closed bag was discovered and seized. Thus there was no danger of evidence being lost. The government does not argue this was a search incident to a lawful arrest. Nor were the contents of the bag in plain view. The container was not of a type whose outward appearance reveals its contents.