Tuesday's proceeding in Montgomery County stems from a petition filed by a citizens group that wants the Barnes Foundation to stay in suburban Lower Merion.
The Friends of the Barnes Foundation says Orphans Court Judge Stanley Ott didn't have all the evidence when he approved the art collection's move in 2004.
Ott says he wants the foundation and the attorney general's office, who argued in favor of the move, to explain why the case shouldn't be reopened.
The Barnes galleries are slated to close in June and reopen next year in a new building near the Philadelphia Museum of Art.