While Pope Francis is wowing vast crowds on a triumphant homecoming to Latin America this week, one of the pivotal moments of his papacy is set to begin back in Rome on Saturday with the opening of a criminal trial for former papal diplomat Józef Wesołowski on charges of sexual abuse of minors.

Ultimately, it’s the threat of criminal sanctions from Vatican tribunals that underlies new accountability measures Francis has created to face the two most chronic sources of scandal he inherited when he was elected in March 2013 – sexual abuse and financial misconduct.

The Wesołowski trial is the first major test of that criminal justice system under Francis. And it will have a great deal to say about whether this pontiff’s celebrated vow that there will be no “daddy’s boys” on his watch, meaning clerics able to remain above the law, actually has teeth.

Now 66, Wesołowski was born in Nowy Targ, Poland, in 1948, and ordained a priest by Cardinal Karol Wojtyła of Krakow, the future St. John Paul II, in 1972. Wesołowski served as a papal diplomat in a variety of nations in the late 1990s and 2000s, eventually being named the nuncio, or ambassador, to the Dominican Republic in 2008, holding the rank of archbishop for papal envoys.

He resigned as the nuncio to the Dominican Republic in 2013 amid allegations of child abuse, including charges that he was in the habit of picking up underage “shoeshine boys” in Santo Domingo, the Dominican capital, and paying them for sexual acts.

Wesołowski was recalled to Rome in August 2013 and faced an internal ecclesiastical probe, which led to his being laicized, or removed from the priesthood, in June 2014. In itself, laicization is a rare step for a bishop, and a clear signal the Vatican believes the charges against him have merit.

Since the scandal broke, the question has arisen of why Wesołowski hasn’t been sent packing back to the Dominican Republic to face criminal charges. While the Vatican has said it would comply with any extradition request, it also insists that because Wesołowski was holding a Vatican passport at the time of the alleged crimes he first has to face sanctions under the Vatican’s own criminal law.

In effect, Francis himself created the legal basis for the trial in July 2013 by issuing an edict known as a motu proprio specifying that criminal laws of the Vatican City State are also applicable to employees, such as ambassadors, stationed in other parts of the world.

Last month a Vatican spokesman announced the Wesołowski trial would open on July 11, and predicted it would wrap up early in 2016. In addition to his conduct in the Dominican Republic, Wesołowski faces charges related to pornographic images reportedly discovered on a personal computer while living in Rome after his recall.

The Rev. Federico Lombardi, the Vatican spokesman, said the trial would draw upon both information transmitted by investigators in the Dominican Republic and IT analysis by Vatican experts. The Vatican’s criminal tribunal is headed by a lay jurist named Giuseppe Dalla Torre, a longtime professor of law at the University of Bologna.

The Vatican does not have jury trials. Hearings are conducted before a judge, and if the initial procedure results in a conviction the accused party can appeal to a three-judge tribunal and ultimately to a Corte di Cassazione, or Supreme Court. Accused parties have the right to a public defender.

If he’s convicted, Wesołowski could face a sentence of six or seven years in prison on each count as well as a steep fine. That term could be served in a Vatican facility, though in the past when a Vatican court has imposed a lengthy sentence it’s generally been served in an Italian prison.

Aside from the details of Wesołowski’s personal situation, his case is key because no matter what happens it will set a precedent.

The last time a Vatican criminal court held a high-profile trial it was October 2012. And it lasted only four days. Former papal butler Paolo Gabriele admitted to stealing Vatican documents and leaking them to an Italian journalist, and was sentenced to 18 months in prison. He was given a full pardon by Pope Benedict XVI two months later.

This time around, presumably, if Wesołowski is convicted a pardon seems highly unlikely.

With Gabriele, Benedict himself was the injured party and fully within his rights to decide to let the perpetrator off the hook. With Wesołowski, the real injured parties are the minors he allegedly abused, and Francis probably would not take it upon himself to waive the legal consequences of Wesołowski’s actions.

Ultimately, it’s precisely those consequences that form the bedrock of the pope’s new accountability systems. Both with sexual abuse and also various financial crimes, such as money-laundering and embezzlement, the new systems envision preliminary investigations by Vatican agencies, whose ultimate power is to refer the matter to the Vatican’s criminal prosecutor for possible charges.

Insiders and outsiders alike thus will be watching to see how Wesołowski’s trial plays out.

If the impression is of foot-dragging and cover-up, the take-away will be that promises of accountability ring hollow. If the trial unfolds in a transparent manner and, assuming guilt is established, a sentence commensurate with the crimes is imposed, then reasonable observers will conclude that the era of “daddy’s boys” in the Church really is over.

Francis, of course, knows what’s at stake. That’s why throughout this busy week on the road, he’ll no doubt keep one eye on what’s happening back in Rome.