The Pope has called for the abolition of capital punishment and declared life imprisonment "a hidden death penalty".
In a meeting yesterday with representatives of the International Association of Penal Law, Pope Francis said: "All Christians and people of good will are thus called today to struggle not only for abolition of the death penalty, whether it be legal or illegal and in all its forms, but also to improve prison conditions, out of respect for the human dignity of persons deprived of their liberty.
"And this," he continued, "I connect with life imprisonment. Life imprisonment is a hidden death penalty."
Other aspects of the legal system which came under fire from the Pope were illegal uses of torture, the detention of prisoners without trial, stereotyping groups of people deemed to be "threatening" and maximum security practices which utilise isolation techniques.
This can lead to "psychic and physical sufferings such as paranoia, anxiety, depression and weight loss and significantly increase the chance of suicide," he said, according to the Catholic News Service.
Pope Francis suggested that penalties given to elderly criminals should be limited, as older people "on the basis of their very errors can offer lessons to the rest of society.
"We don't learn only from the virtues of saints but also from the failings and errors of sinners," he added.
The Pope's wide-ranging address also highlighted human trafficking, which he said could never be committed without the "complicity, whether active or passive, of public authorities".
"Corruption is an evil greater than sin. More than forgiveness, this evil need to be cured," he said.
Last year, Pope Francis gave one of his strongest sermons in which he denounced those who engage in corrupt practices and insisted they must be punished.
"Where there is deceit, the Spirit of God cannot be," he said during a Mass in the Vatican's Santa Marta.
Quoting a passage from chapter 17 of the Gospel of Luke, the Pontiff reminded his audience that Jesus says "It would be better for him if a millstone were put around his neck and he be thrown into the sea".