Many. Some in court are given another chance when the judge understands the medical nature of the problem COMBINED with the individual's determination to take their medication and follow up with their treatment plan. Some given medications that make them worse - such as Elavil (amitryptilline) - can be a defense in court.
Domestic violence is a huge problem. Getting control of dysphoria is crucial. It is the individual's responsibility to be under control - particularly when methods to do so are available.
Substance abuse is also a problem. Borderlines frequently self-medicate with the wrong drugs and end up with two problems - the BPD and a drug dependency. Legal problems can be overwhelming.
Borderlines are "allergic" to alcohol and should never use it. Dysphoria (anxiety, rage, depression and despair) can develop as a withdrawal "seizure" 12-72 hours later, and combining a medication - alcohol - that inhibits the thought processes and allow rage to take over when stressed is very, very dangerous. Only one episode of losing control is enough to create a tragedy and ruin a life permanently.
Divorce, family court, and child abuse are the biggest problems however. Divorces are extremely common. Due to abandonment induced dysphoria, many borderlines go out of their way to get even with their spouse for wanting a divorce and hurt the spouse and the children to get even. Vengeance is the most hurtful human emotion. False accusations can be very hard if not impossible to defend against, and eventually everyone loses except the lawyers. Children are always hurt by false accusations by one parent against another. The children's best interests must always be at the top of the priority list. Sometimes untreated borderlines are indeed unfit to be with their children, however this is a legal issue not a medical one. Rage and dysphoria can be taken out on children, even without this intent. That's another reason treatment is so important. Integrity once again is crucial. So is diagnosis and treatment. The best thing anyone can do in this situation is see a therapist to make sure you and/or the children are doing the right things, and often consult with a lawyer before problems get out of control.