A death row inmate who says anti-gay bias tainted his sentence wants last term’s U.S. Supreme Court ruling on racial bias in the jury room to save him. But a legal scholar told Bloomberg Law the inmate may be raising the issue too soon.

The case pits two evolving areas of the law against one another: gay rights and the sanctity of the jury room.

Charles Rhines points to the Supreme Court’s divided decision last term in Peña-Rodriguez v. Colorado...