Francis’s purpose is simple: He favors the proposal, put forward by the church’s liberal cardinals, that would allow divorced and remarried Catholics to receive communion without having their first marriage declared null.

Thanks to the pope’s tacit support, this proposal became a central controversy in last year’s synod on the family and the larger follow-up, ongoing in Rome right now.

But if his purpose is clear, his path is decidedly murky. Procedurally, the pope’s powers are near-absolute: If Francis decided tomorrow to endorse communion for the remarried, there is no Catholic Supreme Court that could strike his ruling down.

At the same time, though, the pope is supposed to have no power to change Catholic doctrine. This rule has no official enforcement mechanism (the Holy Spirit is supposed to be the crucial check and balance), but custom, modesty, fear of God and fear of schism all restrain popes who might find a doctrinal rewrite tempting.