NEW YORK/WASHINGTON (Reuters) – Volkswagen AG (VOWG_p.DE) will probably have to show there was some legitimate reason to install software that led to false vehicle emissions tests if it is to avoid U.S. criminal charges, lawyers said on Tuesday. As a result it is almost certainly exposed to very large civil penalties that could be imposed by the U.S. government, said attorneys with expertise in environmental prosecutions though not involved in the Volkswagen case.