Time to combine segments from my two lives, that of a law student, and that of a journalist.
Key in any trial is the testimony of eye witnesses. In fact, in life in general we pay a lot attention when someone says, "I saw it with my own eyes." But how reliable is that testimony? Obviously the further away you get in time, the fuzzier the memory is going to be. But in some cases it isn't about memories becoming fuzzy, it's about them changing altogether.
The concept of a false memory is nothing new. A study by Elizabeth Loftus and colleagues using Bugs Bunny showed that it's possible to convince people that they saw Bugs wandering around Disneyland when they visited the park, even though he's the creation of Walt Disney's competition. The memories seem real though, people reported seeing the rabbit with Mickey Mouse, or shaking his hand, but that couldn't have happened.
You could argue that this isn't surprising. In most cases, it would have been a long time since the original visit that was now being remembered, but that's not the case for the latest work. The study by Dr. Kimberley Wade demonstrated that if you show someone video of an event, but video that's been altered, then that changed version will frequently replace their own memory. Suddenly they're remembering details of something that never actually happened.
That's concerning. Today it's very easy to doctor photographs or videotape with a home computer, and that can be used to influence a person's thinking. Even conversations or still images can change memory. If you look at how most journalism or police work is done, it's rare to get to a witness immediately, and any interference before you get a statement down on paper could lead to a false memory, that the witness sincerely believes. And in court cases, it can be months or even years until they get into court, so who knows how much memory can change.
Even for the rest of us, there are concerns. Marketers love drawing on nostalgia, it's a great way to make us buy products. What if they position products so that it looks like you have used it before. Suddenly you're in the grocery store buying stuff you remember, even if in reality, it's completely novel.
Can you trust your memory? Not completely, so if you want to really keep track, either write it down, or horde your video and still pictures carefully. You never know when your memory might be changed...