A video which allegedly shows American singer R Kelly having sex with an underage girl will be shown in court to members of the public and the media.
Prosecutors claimed the tape was too explicit to show to the public
A judge in Chicago ruled the tape was "the whole crux and lynchpin of the case" against the double Grammy winner.
Kelly - who has sold more than 23m albums worldwide - has denied 14 counts of child pornography.
It is three years since the allegations were first made against him, but the case has still not come to trial.
Prosecutors claim the tape was recorded when the girl in question may have been as young as 13.
Along with defence lawyers, they had asked Judge Vincent Gaughan to restrict the viewing of the video to only himself, jurors and the legal teams in court.
They claimed the contents were so explicit that they would embarrass the girl, who is now 21.
But the judge ruled there was no "overarching interest" in banning the tape from public view.
Kelly's hits include I Believe I Can Fly and She's Got That Vibe.
He has worked with stars such as Michael and Janet Jackson, Whitney Houston and Mary J Blige.
In 2004, he won seven out of the eight categories in which he was nominated at the Billboard R&B/Hip-Hop Awards.