“ Congress might have provided in that Act that a woman is entitled to compensation so long as she is still deemed to be the lawful wife of the decedent under State law, as, for example, where a foreign divorce obtained by her is without constitutional validity in the forum State. ”

“ The single, unentangled question before us is whether, on these unchallenged facts, Julia was at the time of Otis' death in 1951, his statutory 'widow,' as that term is described by Congress in the Longshoremen's Act: 'The term 'widow' includes only the decedent's wife living with or dependent for support upon him at the time of his death ”