The Limits of Papal Infallibility
Father Nicholas Gruner remarks in his book, Crucial Truths to Save Your Soul: “By a special grace, Popes are preserved when they are defining dogma, but at all other times even the Pope can fall into errors.” Such a statement is based on the Church’s dogmatic definition of Papal infallibility which is often misunderstood. In his book, Catholic Apologetics, Fr. John Laux states regarding papal infallibility:
“The [First Vatican] Council did not declare that the Pope cannot sin; neither did it declare that he can in no way err; nor that he cannot personally hold erroneous views in matters of faith; but merely that he is infallible, not subject to error, when he decides ex cathedra – that is, as Head and Teacher of the whole Church – upon matters of faith and morals.”
Far from merely an intellectual exercise, history indicates that Popes can be guilty of prudential errors and governing debacles. They can enforce unjust legislation and enforce decrees against the common good. They can certainly be immoral and fall into mortal sin. They can hold errors in personal beliefs and even teach error in catechesis and doctrine. None of these contradict the grace of infallibility bestowed upon the Papal Office by God. The Pope only exercises his [negative] charism of infallibility when,  as Teacher of the Universal Church, he  defines a matter of faith or morals  which must be accepted and believed by all of Christ’s disciples.
A Brief Explanation of the Power
It is called a charism because it is a special gift that comes from the Holy Ghost. This charism is part of the papacy. In other words, it is not given personally to an individual man but rather is a power that is exercised by virtue of the authority of the Papal Office (recall the keys given to St. Peter by Christ, in Mathew 16). It is a ‘negative’ power in that it prevents something, namely error. It does not guarantee that what is proclaimed infallibly is said in the best or most perfect way, but merely that what is defined infallibly is prevented from being erroneous.
When using the power of infallibility, the Pope must make it clear that he is in fact using his full magisterial (teaching) authority to bind all Christians. The Pope must likewise make it known that this is a matter of faith or morals; and he makes the effort to show that this teaching is contained within Divine Revelation (i.e., Sacred Tradition and Holy Scripture). The Pope is obligated to make these points clear because our salvation requires that we submit to all infallible dogmas. Thus, there should never be any confusion or ambiguity regarding if a Pope has used the infallible charism of the Papal Office to bind all Christians to accept a dogma.
Two good examples you can look up are when Pius XI declared the Immaculate Conception (Ineffabilis Deus, 1854) and when Pius XII declared the Assumption (Munificentissimus Deus, 1950). These documents set a precedent and clearly demonstrate how a Pope today would issue an infallible statement.
You can read more on Papal Infallibility here or listen to Fr. Albert explain papal infallibility in an Ask Father episode posted May 5, 2023 (video / podcast).
Vatican Council One on Papal Infallibility
If you wish to study the Church’s formal teaching on Papal Infallibility, then read Chapter IV of Pastor Aeternus, the dogmatic constitution promulgated by the First Vatican Council (1870).
The Council Fathers explain that “new” doctrines cannot be proclaimed. They must be part of the Deposit of Faith from the Apostles.
The Council Fathers further teach that this gift is at the service of truth and the salvation of souls. A consequence thereof is that it also fosters unity (which can only be found in truth).
And they provide the formal definition of the dogma, clearly stating it must be believed under penalty of falling outside the only ark of salvation (anathema):
“We teach and define as a divinely revealed dogma that when the Roman pontiff speaks ex catehdra, that is, when, in the exercise of his office as shepherd and teacher of all Christians, in virtue of his supreme apostolic authority, he defines a doctrine concerning faith or morals to be held by the whole Church, he possesses, by the divine assistance promised to him in blessed Peter, that infallibility which the divine Redeemer willed his church to enjoy in defining doctrine concerning faith or morals. Therefore, such definitions of the Roman pontiff are of themselves, and not by the consent of the Church, irreformable. So then, should anyone, which God forbid, have the temerity to reject this definition of ours: let him be anathema.”
To Be Continued….
READ PART II of this article, in which we examine various examples from the lives of the Popes who did in fact err – and err gravely.
 A ‘positive’ power would enable a person to do something; for example, Holy Orders gives the priest the power to turn bread and wine into the Body and Blood of Christ when using proper matter, form, and intent. A negative power prevents someone from doing something. Similarly, a negative commandment says thou shalt not do such and such; for example, Commandments Five though Ten. Whereas a positive commandment is thou shall do this or that; for example, ‘Thou shall love the Lord thy God with all thy heart, soul, mind, and strength (cf. Mk 12:30) or ‘do penance, lest ye perish’ (cf. Lk 13:3,5).
 “For the Holy Ghost was promised to the successors of Peter not so that they might, by his revelation, make known some new doctrine, but that, by his assistance, they might religiously guard and faithfully expound the revelation or deposit of faith transmitted by the apostles.” (Pastor Aeternus, Chapter IV, No. 6.)
 “This gift of truth and never-failing faith was therefore divinely conferred on Peter and his successors in this see so that they might discharge their exalted office for the salvation of all, and so that the whole flock of Christ might be kept away by them from the poisonous food of error and be nourished with the sustenance of heavenly doctrine. Thus the tendency to schism is removed and the whole church is preserved in unity, and, resting on its foundation, can stand firm against the gates of hell.” (Pastor Aeternus, Chapter IV, No. 7.)
 Pastor Aeternus, Chapter IV, No. 9.