Usage and Grammar

Q. Please distinguish between per and as per.

A. They are the same. As per used to be considered a barbarism, and editors learned to change it to per (or reword it into English). CMOS 5.250 still warns against as per: “This phrase, though common in the commercial world, has long been considered nonstandard. Instead of as per your request, write as you requested or (less good) per your request. The recent innovation as per usual for as usual is an illiteracy.” You will find, however, that popular usage is winning the day, and that as per is treated as standard English by authoritative sources such as Merriam-Webster and the OED.