IANAL, but I think what he said is probably true in many, but not all courts.
He’s right of course, it’s simple to fake any digital picture. But what if you took a picture using a regular 35 mm film camera for example. I think an expert could testify whether it had been altered or not. Videos, OTOH, are not as easy to fake and digital pictures.
An unbiased witness, other than someone from your family of course, would be even better since attorneys could ask the witness questions about what they did or didn’t see. A witness, of course, can also be “faked” but they have a word for that… perjury.
I’ve heard of no such common belief, and it sounds pretty dubious to me. The way a photo (digital, film or whatever) gets introduced in court is either that both sides agree it is authentic, or you show it to a witness who is testifying, and ask them whether it accurately represents whatever it is claimed to represent. Then the jury gets to judge for itself.
If a lawyer for the other side wants to challenge the authenticity of the photo, he is free to get up and cross-examine the witness, e.g. “how can we be sure this wasn’t photoshopped? did *you *photoshop it? aren’t you just lying for financial gain or to spite my poor client?” etc. … The likelihood that the jury will find that this cross-examination lessens the weight they would otherwise give the photo probably depends on what other evidence there is, and whether the lawyer has any evidence to show that any photoshopping took place. Bare cross-examination along these lines, though, is probably going to fall pretty flat as long as the witness simply tells the truth, e.g. “no, I didn’t photoshop it and to my knowledge it hasn’t been photoshopped.”
If you really want to allay any suspicion, though, why not just take old-timey photos on real film? When the shyster on the other side gets up to make wild and unfounded accusations about their authenticity, you can shove the negatives down his throat.
I’m a prosecutor. We use photos all the time, for many different types of cases. Remember, a photo doesn’t just float in and get introduced as evidence all on its own; it has context. Usually, we provide that context with the person who took the photograph.
It goes something like this: “Mr. Photographer, did you take this picture on Date?” “Yes I did.” “Can you identify all the persons in this photograph?” “Yes I can.” Then the important question: “Does this photograph fairly and accurately depict what you saw on Date?” “Yes it does.” “I move to admit this photograph blah blah blah.”
See, the attorney doesn’t just toss the photo at the judge and ask that it be admitted. First, a person has to testify under oath that the photograph is an accurate representation of what he personally saw. After that, the photograph is considered reliable enough to be admitted.
Those questions (which I’ve really abbreviated above, by the way) are called “predicates”, and we keep lists of them for introducing the various types of evidence. The predicate questions for introducing a videotape are actually a lot more complicated than those for introducing a photograph, because you have to verify that the equipment was functional, that the operator was trained and competent, that the witness can identify all the voices on the tape…it goes on quite a while.