Ian Hurst wrote:
Do not try and describe the fight in your own words, even if you feel you were clearly in the right, until you have consulted a lawyer. Especially do not use any words that would indicate any particular training, ability etc (and don't offer that information directly). If pressed for an answer, be helpful yet vague on the details until you have a professional at your side who will ensure you are not damaging your case and always do what the nice police officer tells you to do immediately. Unless your lawyer tells you it's a good idea, forget all words such as martial arts, aikido etc. Do not assume you are being seen as the "good guy" in any encounter.
You do want to get the fact that a) you were "afraid" for your own safety and b) that you did something to try to forestall the encounter (I told him I didn't want to fight, I tried to leave but he followed me out, etc.) Be especially careful to make sure that as many people as possible heard you say so or saw you try to get away. If the assailant had indicated his violent intentions verbally you want that in the report immediately so the police can corroborate with other witnesses.