As I understand our USA legal system, some sort of (new, since the 2015 ruling) restriction on SSM only would have to be made a law somewhere in the USA (maybe as low level as a City Ordinance) and would have to go all the way thru the State and Federal court system all the way up to the Supreme Court and be upheld.
Then other SSM only restrictions/laws would likely be tried, just to see what the Supreme Court would uphold.
(maybe a lawyer here on UBF could expand on this scenario)