Law enforcement representatives from both the state and local level have submitted a proposal to the US Congress that would require mobile carriers in the US to keep SMS logs for all users for at least two years, just in case they're eventually needed for future criminal investigations. The law enforcement reps say that the lack of a current requirement "can hinder law enforcement investigations."
Lawmakers are currently considering amending the 1986 Electronic Communications Privacy Act in order to make it more relevant in today's internet era, and the Major Cities Chiefs Police Association and other enforcement groups want to have a say during the amendment. They argue that text messaging conversations often contain evidence that can be vital to investigations, and current policies among US cellular providers are claimed to be inadequate.
Currently, most carriers store rudimentary data for text messages from the past few months, but the actual content of the text messages are usually only held onto for a few days. According to a Justice Department memo from last year, Verizon stores detailed SMS logs for between three and five days, while AT&T and T-Mobile keep no such records whatsoever. Carriers might have changed their policies since then, but regardless, standardizing a new logging practice for a specific amount of time would give law enforcement agencies confidence that the logs are there if they need them.
Obviously, this will no doubt spark privacy concerns, and the privacy advocates will be out in full force. While your text messages will most likely not be bothered with as long as you're a good boy or girl, knowing that carriers and law enforcement have access to your detailed SMS logs from the past two years certainly isn't assuring.