Can any academic lawyer help on this: consider a citation to

Hamdan vs Rumsfeld, 548 US 557 (2006)

Is there any circumstance in which one would wish to be able to access the volume number (here, 548) separately from the name of the reporter (here, the US reports), or vice-versa? Reason: I'm designing a biblatex citation style; my original thought was to create a single field containing both bits of information (so one would enter "548 U.S."), and I was wondering if that might be a bad decision. Any help gratefully received.