Dear [town] Police department:
My name is [name]. My address is [address]. My telephone contact number is: [phone]. My email is: [email]. My car is [make, model license number]. I was stopped by police on [date] at approximately [time] at [address of stop]. I am considering legal action based on that stop and/or actions taken at that stop. Please:
(i) do not erase or destroy or otherwise tamper with any video and/or audio of the stop (including any recordings of things that happened before and after the stop) because it is likely to be important evidence in any legal action I may choose to bring and all of these recordings (if any) should be preserved for that reason;
(ii) if any recordings as described in the previous point (i) would otherwise be destroyed in the normal course of your business, do not do that in this situation to avoid the possibility of spoliation of evidence now that you have been put on notice (by this letter) of the special significance of these recordings; and
(iii) if possible make me a copy of any recordings as described in point (i), above, so that I can best evaluate my next steps.
Sincerely,
[stopped guy]