Hugo Black, contrary to some dumb conservative arguments, was an effective advocate for civil rights and civil liberties for most of his tenure on the Court. But he stayed on a decade or so too long, and there were times during the height of the civil rights movement where a bit of you-can-take-the-boy-out-of-Jim-Crow-Alabama would surface. I love this dispute between Black and William O. Douglas over civil rights recounted in Scot Powe’s The Warren Court and American Politics, where Douglas gets to the heart of the issue with secular for-profit corporations claiming the right to “exercise” religion at the expense of the rights of their employees:
Black was quite clear that either the state or federal government could mandate the restaurant serve everyone, but if the law was neutral, the property owner prevailed…He saw the situation in terms of his father’s store in Ashland, Alabama, and related that he believed “Pappy” would have the right to decide whom he was going to serve in his store.
Douglas, who had been inseparable from Black in the earlier periods, was now his opposite, and he was hardly interested or impressed with Black’s childhood or his father’s store because they were irrelevant to the issues before the Court. Douglas had no tolerance for the idea that S.H. Kress or Woolworth’s or McCrory’s was a mom-and-pop store where ownership and management merged. “The corporation that owns this restaurant did not refuse service to these Negroes because “it” did not like Negroes. The reason “it” refused service was because “it” thought “it” could make more money by running a segregated restaurant.” 
Quite so. And this is also relevant to whether secular companies should be able to claim religious exemptions to civil rights laws covering sexual orientation.