The episode is Doped. It's a "ripped from the headlines" story. A few months ago some poor woman drove the wrong way down a highway, drove headlong into another car, killed herself, and the people in the other car. Supposedly she was drunk, although family and friends said she never touched alcohol. And of course if it isn't bad enought that the husband has lost his wife and I think one or more of their kids, the family of the people who died in the other car filed a lawsuit against him, trying to gouge him and his insurance company for all he's worth. (Apparently, if TV commercials are to be believed, people can be sued for more money than they are covered for in their insurance, and if the person has wealthy parents, their stuff can be taken away, too. )
In any event, of course in the Law and Order version, the woman was deliberately doped, to cause the crash, to kill her. Heck, it may have been that way in real life, too. But in any event, kind of a sick thing to make into a TV episode.
Of course, Law and Order quite frequently does these ripped from the headlines stories. They did one about the woman who ran over a homeless person, who was impaled through her windshield, and lived in her garage for two days until he died. Then she and a few friends dumped his body...but they were caught and she's now doing time. In real life, this was a Hispanic woman, in the TV episode, of course it was a white woman. And the "twist" of course was that in the episode, the guy was actually dying of a beating, the woman hadn't killed him even though he'd been in her car windshield without her trying to help him, so she gets off with a warning for "concealing evidence."
(Not that white folk aren't capable of committing heinous crimes...but whenever Law and Order does these types of episodes, typically the race in the ep is always white, regardless of what the real race of the person in real life was. Little bit of political correctness there.)