Sometimes I run across odd bits of research that I think readers might be interested in, and this is one.
The Catholic Church is about to get a new Pope and if anything can make federal civil procedure look simple and straightforward, it's canon law. Which brings me to the doctrine of papal infallibility, which non-Catholics sometimes ask me about, usually in the context of how cool it would be to have His Holiness on their Trivial Pursuit team. (Which it would, obviously, since he would just crush questions on medieval theology, and probably European soccer as well).
First, of all, obviously popes sometimes say and do the wrong things, so infallibility is not across the board (for example, reputedly Benedict does quite poorly on Vatican sports pools). According to the First Vatican Council in 1870, it is limited to when the Pope speaks ex cathedra (literally 'from the chair' of Peter) and "defines that a doctrine concerning faith or morals must be held by the whole Church". So it's an extremely narrow range of pronouncements, made only rarely.
How rare? Well, the only instance I am aware of in the entire 20th century was when Pius XII made a declaration regarding the Assumption of Mary in 1950. In fact, there are only seven statements which are generally agreed to have satisfied the standards for infallibility since 449 A.D., although theologians and writers argue as to whether other statements satisfy the test as well. (They have actually been busy since 1653, with one each in the 17th, 18th, 19th and 20th centuries, so by Vatican standards, the doctrine has some momentum). I think Pope John XXIII touched on both the limited nature of the doctrine and its rarity when he memorably said "I am only infallible if I speak infallibly but I shall never do that, so I am not infallible". (It was funnier in Latin).
This means that a doctrine proposed by a pope as his own opinion, unless proclaimed as a doctrine of the Church (and have I mentioned how rarely that happens?) may be rejected as false even if it is on a matter of faith and morals. And don't get me started on any view a pope expresses on other matters. Benedict rocking the double-breasted cassock and Grinch hat is a good example of the latter at work here.
Enjoy the retirement, Holiness. And let's look into some jogging suits, okay?