"I will be examining the cardinal myself and I'm anticipating I will be making a finding of competency," Sarmina told lawyers in the case.
His testimony could last hours or days, she said.
"I can't speak to the cardinal's stamina," Sarmina said. "It could be a few hours on Monday, a few hours on Tuesday, a few hours on Wednesday, a few hours on Thursday."
The decision sets up a historic showdown between the cardinal who led the region's Catholics for 15 years and the districts attorneys who argue that the archdiocese, under his leadership, routinely concealed child-sex abuse by shuffling predator priests among parishes and failing to tell the members of those churches.
Bevilacqua has not been charged, but prosecutors say his testimony is critical to their case against Msgr. William J. Lynn, a former ranking aide accused of conspiracy and child endangerment for allegedly placing abusive priests in positions that gave them access to victims.
Acknowledging Bevilacqua's age and frail health, they asked for permission to question him in a videotaped deposition now, instead of waiting until Lynn's trial begins in March.
Lawyers for Bevilacqua, who retired as archbishop of Philadelphia in 2003, have said he suffers from dementia and isn't fit to testify. He was not called before the grand jury that recommended the charges against Lynn and four others in February.
Brian McMonagle, the criminal defense attorney hired by Bevilacqua this summer, argued that any such proceeding should be private, contending that prosecutors were unfairly trying to expose the cardinal to a medial gauntlet by calling him to open court in Philadelphia.
McMonagle cited a rule in the Pennsylvania code that said only the judge and attorneys need to be present for the questioning.
Lynn faces charges of endangerment for allegedly placing abusive priests in position to assault children. Arrested with him were two priests, a defrocked priest and a former Catholic schoolteacher who prosecutors say molested two boys in the mid-1990s.
Contact staff writer John P. Martin at 215-854-4774, at firstname.lastname@example.org or @JPMartinInky on Twitter.
Follow the Inquirer at www.Twitter.com/PhillyInquirer and www.Facebook.com/PhillyInquirer