Okay, this is my last post in this thread (and hopefully the last one about this topic). For the record, there is evidence that anal sex causes problems for a significant number of people who engage in it. But there is simply no question that the style of anal sex commonly found in porn causes problems (rough penile penetration with plenty of friction). Stuff such as "anal destruction" and "painful anal" are even out there, not to mention other extreme activities such as large anal insertions and rectal prolapse play.

By the way, "under California law, criminal negligence is only concerned with the act itself, not with the consequences." The possibility that "Great Bodily Injury" could occur must be established. California's definition of GBI is: "a significant or substantial physical injury." (edit: alt source) I don't know which physical risks of anal sex might constitute GBI; I'm not a lawyer.

See this* or alternatively, this for the physical risks of anal sex. Several of the quotes have data on how common certain problems are amongst those who engage in anal sex. One notes that, due to the fact that the rectal mucosa is delicate, anal sex is "likely to cause some degree of trauma."


* That site is unmaintained and I haven't touched it for almost a year. It's amazing that it's still up on a free host.