Prosecutors allege that the clinic, Women's Medical Society, at 3801 Lancaster Ave., performed illegal late-term abortions and that Gosnell killed seven infants born viable.
Lerner issued the gag order on his own initiative.
Later, the question of why Pearl Gosnell got a "cell toss" was raised by her newly hired lawyer, Michael Medway.
He said that sometime after April 4, when Lerner reduced the wife's bail from $1 million to $50,000, representatives of the District Attorney's Office, with a subpoena and the approval of prison officials, seized personal letters between the Gosnells.
Medway said that under court rules, the prosecutor may not have contact with a charged individual who is represented by a lawyer without that counsel's approval. Moreover, he said, the prosecutor should have obtained a judge-approved search warrant rather than use a subpoena.
Assistant District Attorney Joanne Pescatore called the practice common in her office: "We had information, and we acted on it. We do this regularly to search cells."
Lerner, however, said he believed the practice had been ruled improper years ago, adding, "I'm at a loss for words."
Tasha Jamerson, spokeswoman for District Attorney Seth Williams, said the office would have no comment on the hearing or Lerner's order.
Later, Deputy District Attorney Edward McCann, who heads the office's criminal division, reiterated that position: "I think it's pretty clear to all of us here that the judge doesn't want us commenting about this case."
Prison spokesman Robert W. Eskind declined to comment on the circumstances of the cell search. Though Pearl Gosnell was allowed to sign her own bail bond April 4, Eskind said, she remains in custody until arrangements are completed for her electronically monitored house arrest.
One issue of confusion was whether an order by the supervising judge of the county grand jury that recommended charges against the Gosnells - it barred the 10 defendants from talking to one another or potential witnesses against them - applied to communications between husband and wife.
Though Pescatore told Lerner that everything seized had been copied and returned to Medway, Medway said Lerner should order the copies returned, too, because the search had been improper.
"I don't want the commonwealth to have so much as a shred of paper that was from taken from her cell by a subpoena," Medway said.
The prosecution's justification and the return of any documents was left for a hearing to be scheduled.
"In the meantime, I don't want this happening again until the further order of this court," Lerner said.
In another development, he set June 21 to consider a first round of defense pretrial motions. As the so-called homicide calendar judge, Lerner hears and resolves pretrial motions for all city murder cases before referring them to one of seven homicide judges for trial.
Lawyers for the Gosnell employees have asked Lerner to sever their cases from Kermit Gosnell's. Gosnell is charged with seven counts of first-degree murder involving the infants and one count of third-degree murder involving the death of a woman during an abortion. Prosecutors have said they are considering seeking the death penalty if Gosnell is found guilty of first-degree murder.
One of the employee's lawyers also filed a motion to have the trial moved outside Philadelphia or to select a jury from outside the county.
Contact staff writer Joseph A. Slobodzian at 215-854-2985 or firstname.lastname@example.org.