[robski]

As Andy has said much has been done to help courts with digital photo forgery in recent years. i.e Photoshop will embed it own data to say what has changed from the original. It is possible to edit only the exif data without touching the image using certain off the shelf file editors. But I am sure the exif data will have it's own checksum and that would indicate something has changed. If you were expert enough (i,e somebody who wrote the photo checking software) it would be easy enough to fool the court. The likely hood of the average hacker fooling the system is very small.