Much of what you do every day is recorded some place on some computer somewhere. Whom you called on the telephone, your emails, your ATM withdrawals, what toll booth you passed through, when you turned your office alarm on and off and so on are all logged somewhere. Where there's a record, there is always a risk that somebody will use the information against you. If that makes you feel a bit paranoid, your fears may not be irrational.
One of the things that make computers an incredible tool is that they have this almost inconceivable ability to store massive amounts of information. In many contexts, people often don't know that a computer is keeping a record of their activity. For example, did you know that your car might have the rough equivalent of an airplane's black box in it? If you're in an accident, your black box may have a record of your speed and other information about how you were driving right before the accident.
This raises some interesting questions about who "owns" that black box information. In the end, it may not matter anyway, since a court could subpoena the information even if you "own" it. Moreover, don't even dream of destroying the black box if litigation is possible.
Then consider your office computer. What does it know about you? While you can generally delete documents - especially if your business has a written document destruction policy - the generalization changes once you know you have a legal problem pending.
What still surprises many people is that even when you "delete" things on a computer, it's usually still there for someone to find if they know how to look. Therefore, even proper computer file destruction takes some knowledge and appropriate software.
Assuming that you choose to legally destroy digital records (get good legal advice before you do!), if you aren't technically proficient, you may fail miserably. Did you consider your backups, your browser's history files, which lists websites you've visited, your recycle bin, your "temp" files, and copies of the data on your home computer or laptop?
As a practicing technology lawyer, I will tell you that we usually find what we're looking for if we look hard enough. Some of this digital information is beyond your control anyway. For example, you can't simply call your Internet service provider and say, "Please delete all your logs of my activity." It just doesn't work that way.
If you think I've just written a primer on destroying evidence, I would beg to differ. I think I've written a primer on awareness. Digital recordkeeping is still relatively new and people often have no recognition of the scope of what records are out there.
"Awareness" puts you in a position to do things legally and properly. You need to know when it is proper to destroy information and when you will run afoul of the law.
If you're a businessperson, make sure your business has a written document destruction policy. Then, make sure you follow it. If you don't need a record, destroy it. If you don't, then its only purpose is to give somebody a chance to take it out of context and use it against you.
Remember, even the paranoid have enemies.