California's Supreme Court ruled last May that Nike's comments in a letter to a newspaper should count as 'commercial speech'.
Nike wrote the letter to the editor in response to criticism from activists about its labour practices. The court ruled such speech must be held to the same standard as advertising, as it is aimed at customers and is intended to promote sales.
The court ruled 4-3 that Mark Kasky of San Francisco could sue Nike for its statements disputing workshop-condition accusations.
It was announced this week that the US Supreme Court would hear an appeal to the California decision, and is expected to rule by June.
Public Relations Society of America president Reed Byrum said: 'We're gratified the court will take a deeper view of the issue of continuing to protect the First Amendment for society in general. If the (Supreme) Court upholds the California ruling, corporations and their spokespersons will be silenced.'
Council of PR Firms president Kathy Cripps said her organisation would support Nike by continuing to write letters to the editor and ensuring the issue remains 'front and centre'.
'Some publications haven't differentiated the matter as a PR versus ads issue,' said Cripps. 'Some reports have made it sound like it has to do with advertising. The media often doesn't take the time to differentiate between them.'
Byrum said the PRSA would focus on writing op-ed pieces and giving speeches 'to try and educate our society members and the general public about the First Amendment concerns of this case'.