Prosecutors in Italy are seeking a six-year jail term for deputy prime minister Matteo Salvini over a decision in August 2019 to stop a migrant boat from docking.
The ship, operated by the Open Arms charity, was kept at sea for almost three weeks before being allowed to dock on the island of Lampedusa following a court order.
Salvini, who was then the interior minister, denies charges of kidnap and dereliction of duty.
On Saturday, he said he had wanted to stop Italy becoming a "refugee camp for all of Europe" and declared himself "guilty of defending Italy and Italians".
The Opens Arms ship was carrying 147 migrants who had been picked up off the Libyan coast when it was prevented from docking in Lampedusa.
The island, situated around halfway across the Mediterranean towards the Italian mainland, has over recent years been a landing point for thousands of migrants trying to enter Europe.
As interior minister, Salvini implemented a "closed ports" policy that he argued would remove incentives for people smugglers.
Crewmembers have testified during the trial that the migrants' wellbeing and sanitary conditions on board the ship deteriorated while it was being held offshore - resulting, among other things, in a scabies outbreak.
Prosecutor Geri Ferrara told the Sicily court that there was "one key principle that is not debatable".
"Between human rights and the protection of state sovereignty, it is human rights that must prevail in our fortunately democratic system," he said.
In January, Salvini testified that he had understood that "the situation [on the ship] was not at risk".
A verdict in the trial, which began in October 2021, could come next month. If convicted, Salvini could also be blocked from holding government office.
Responding to the requested sentence on X, Salvini said that "defending Italy is not a crime and I will not give up, not now, not ever".
"Thanks to my government's actions, landings, deaths, and disappearances in the Mediterranean Sea decreased," he said.
"This Spanish ship was never prevented from going anywhere, except to Italy. We could no longer be the refugee camp for all of Europe.
"No government and no minister in history has ever been accused or put on trial for defending the borders of his own country."
According to UN data, sea arrivals in Italy fell to 11,471 in 2019, significantly lower than the figures in the years before or since.
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Salvini is the head of the League party, which opposes illegal migration, and serves in a coalition government with Prime Minister Giorgia Meloni's far-right Brothers of Italy party.
On Saturday, Meloni offered Salvini her "full solidarity".
"It is unbelievable that a minister of the Italian Republic risks six years in prison for doing his job of defending the nation's borders, as required by the mandate received from the citizens," she wrote on X.
"Turning the duty to protect Italy's borders from illegal immigration into a crime is a very serious precedent."
