WASHINGTON — Reports that the wife of Supreme Court Justice Clarence Thomas implored Donald Trump’s White House chief of staff to act to overturn the 2020 election results have put a spotlight on how justices decide whether to step aside from a case.Individual justices make their own unreviewable calls on a court that lacks a code of ethics. And the issue is not always clear, particularly when spouses also have prominent careers.While the Supreme Court did not step into any election cases brought by Trump and …