DOJ urges justices to strike down California's Prop 8
News breaks as White House stays mum on filing
Other briefs filed by businesses, 'red state' coalition, GOP
Deadline to file brief is Thursday
Lawyers argue measure labels LGBT families as 'second-rate'
Obama says DOJ 'looking' at filing a brief
Brief says supporters' religious views shouldn't invalidate measure
'Gov't should not put its seal of approval on that unholy union'
Child Trends says its research doesn't pertain to same-sex parents
Attorneys cite inability of gay couples to procreate
