The High Court will rule today on a bid by the teenage son of Environment Secretary Caroline Spelman to continue a privacy injunction.
Earlier this month, Jonathan Spelman, 17, was granted the order by Mr Justice Lindblom preventing the publication of sensitive personal information in the Daily Star Sunday.
The judge said the information, which was leaked to the newspaper, attracted a reasonable expectation of privacy and publication would not advance the public interest.
Last week, Mr Justice Tugendhat was asked to continue the injunction until trial because it was likely that a court would find that Jonathan, who sued through his mother and father, Mark, had a reasonable expectation of privacy and that the public interest did not justify interference with his rights.
Christina Michalos, counsel for Express Newspapers, said the case was about "freedom of expression in its purest sense" and the court should not muzzle the "watchdog function of the press".
She denied that the real motivation of the story was political and focused on Jonathan's mother.
"This is disputed strongly. We say there is an underlying public interest in the story itself."