<p>It is generally advisable for an alien to carry his passport while    in the US. Generally the police in California are not concerned    with the visa status of aliens unless they have committed a serious crime. Usually    all that they are seeking is some form of valid identification such as a driver's    license. However when traveling in other states in the US this may not be the    case and the prudent alien should carry his original I-94.</p>
<p>Many Japanese nationals worry about drunk driving convictions and their effects    upon their visa status. Drunk driving will not affect the alien's visa status    unless as a result of the drunk driving someone is seriously hurt or killed.    The general rule is that the alien must commit a crime involving moral turpitude    (robbery, murder, assault, etc.) to affect his visa status. Note that the alien    will be imprisoned if convicted of a serious crime.</p>