The federal government outlaws "knowingly accessing a computer without authorization or exceeding authorized access" to obtain information from any "protected computer" (which, in this context, means any computer involved in interstate commerce - which, in practice, has been ruled such that it certainly includes any Internet-connected server of a corporation).

Your defense would have to be that you were authorized to access the data, or that you did not know that you weren't authorized to access the data. Not merely that the data was easily accessible.