That's easy. Stalkers.
See, here's the thing. I don't know whether most of my clients "did it." And it's not really that important to me. Sometimes clients come out and tell me, sometimes I have a hunch. But, with stalkers, you always know.
How do you know? Because they stalk you. And, here, by stalk, I mean "call you or write to you endlessly."
So, for example, in court you're assigned a client who is accused of stalking his ex-girlfriend. Ex-girlfriend says he called, oh, I don't know, twenty or thirty times in a few hour period, then showed up at her job. She got scared and called the police. You interview the client, he's released, and you give him your card.
If this client calls you once or twice every few weeks to check in and ask how his case is going, I'd bet he didn't "do it." How do I know? Compare it to this...
After the case, you head back to your office. Maybe you stop for lunch or run an errand. If you get back to your office and have 5 or 10 or 20 messages from this accused stalker, you can bet that he "did it." Double your bet if the messages are a little strange or in any way project what might happen if you don't call back.
On a more serious note, I really think that stalking is a sign of mental illness. It might be a sign of obsessive compulsive disorder or something. I mean, anyone in their "right mind," would call, leave a message, maybe they call back in a few hours if it's really important. They're missing that thing in their head that should tell them, "I just called a few minutes ago, I can't call again."
And, what makes it worse, is that a stalker case is hard to try. Any ex-girlfriend worth her salt kept recordings of some of the stranger messages or kept her phone bill which showed hundreds of incoming phone calls. Your best hope is that a jury can relate to, "Hey, he was a jilted lover. He went a little past the norm. It's not a crime." But you're not going to be able to prove that he didn't make the calls.
On the other hand, most jurors can relate to how annoyed, and even scared, the complainant must have been. Heck, we live in a society where people fully supported laws against telemarketers. So we all agree even a few phone calls can be a nuisance. Then, she's a single girl, and here's this guy who already knows so much about her life (her schedule, her voice mail password, where she hid the spare key).
They're hard cases. But moreover, they're difficult clients.
When they tell me, "But I never called her!" It's hard not to say, "How can you expect me to believe that when you've filled my voice mailbox with messages? When you've called me 20 times in an hour?"
It's got to be some kind of O.C.D. Like, instead of washing their hands over and over, they dial the phone over and over.