Sorry to have missed so much of this discussion, lots of interesting points.
Here is another example that happened years ago. This was in the late 80's when "sober stops" had not yet been recognized as being unconstitutional. A guy had a beer after work and headed home. Along the drive, he spotted a pair of cops he knew manning a sober stop and pulled over to say hello. They stood around shooting the breeze for awhile and he thought it would be fun to see what he blew on their breathalyzer. He was sure he was legal so what could be the harm, right? The machine registered him just over the legal limit. The cops had no choice but to book him for DUI since they had seen him drive up. Maybe justice was served by getting a potentially dangerous driver off the road but does anyone think this guy was smart to VOLUNTEER for a breathalyzer test?
This story was from an article in men's health titled something like "10 things men do that screw up their lives." When I get the opportunity to give advice to younger men, I warn them that people often don't distinguish between justice and law. If you have done something wrong (and are not a sociopath) you will feel bad about it. You might be desperate to stop feeling bad about it. Turning yourself over to legal authority MIGHT make you feel better but it will almost certainly open you up to being treated like a pariah for the rest of your life.
Consider the Duke Lacrosse "suspects." I am confident that some of their friends and family urged them to confess to the accusations so "healing" could begin. Now Crystal Mangum is in desperate need of all kinds of healing but a mountan of evidence shows THEY DIDN'T DO IT! Even if they feel guilty about hiring a stripper and being rude to her and embarassing their team or whatever, putting them in jail will not make anyone's life any better.
The same kind of thing happens in DV cases. Accusations of DV happen in an atmosphere of conflict; it is likely both parties have already said and done things they feel bad about. Someone might FEEL abused because her husband forgot to set the VCR to record her favorite TV show. Someone might FEEL guilty because of something he said during an argument. If the police show up at his place of work wanting to question him about "what happened last night" the answer that will make him FEEL better is also the answer that will cost him his livelihood, his home and his children.
Lawyers get guilty people out of jail every day. Their clients sometimes smirk and scoff but plenty of times they tell their lawyer they feel ashamed and miserable. An experienced lawyer knows what to tell them: Tell a priest, tell a bartender two towns over but don't stick your head in a noose trying to feel better; that's not what nooses are for.