Additionally, I've read that the Medici's skirted usury laws... but never with an explanation of how they would have done this. Was the church aware, and did they disapprove?
Follow up question: How would the Medici or another bank of the period verify identity? If I show up in Venice with a letter of deposit made out to Sir so-and-so in London, how do they know if I am Sir so-and-so, or if I'm just the guy who killed him and stole his documents?