Good points Feywon. There was just an episode on 9-1-1 Lone Star where one of the EMTs resuscitated a woman found on the floor after her frantic sister called 911. The woman, a terminal cancer patient was wearing a DNR bracelet but had on long sleeves (which ostensibly covered the bracelet). She woke up soon after they started working on her and was angry and told them she had a DNR, showing the bracelet. She decided to sue the EMT, the fire department and the city for $1 each, just to make her point but also asked that the EMT be fired. The lawyer said the case might work in the EMT's favor because the long sleeves hid the bracelet and the sister never told them of the DNR. Later the EMT admitted that she did see the bracelet but didn't have the heart to let the woman die in front of her sister. At the end, the woman was going to drop the case anyway but died. The sister came to the station and gave the EMT the bracelet, at her late sister's wishes, to remind her that people who request DNRs deserve to be heard and their wishes honored. I really do believe they pull some of these story lines from real life cases
Re the OP: My living will was left with my doctor and the system here is similar to
@jimintoronto described. Other doctor's and I'm sure the affiliated hospitals could access a copy in minutes.