"The vast majority of drug cases potentially tainted by former state chemist Annie Dookhan will be vacated by mid-April, with just a few hundred convictions out of 24,000 remaining on the books, according to district attorneys. The prosecutors have been working on a 90-day deadline issued in January by the Massachusetts Supreme Judicial Court to produce shortened lists of Dookhan convictions they believe must stay in place and are getting close to concluding......... Dookhan, who was responsible for testing drugs in about 40,000 cases at the former Hinton laboratory in Jamaica Plain from 2003 to 2012, admitted to more than two dozen charges of tampering with evidence and fabricating results. She served three years in prison, for perjury and evidence-tampering, before she was released on parole last year. Since Dookhan's misconduct came to light in 2012, defense advocates have called for erasing convictions in any case she touched. They argued that the scale of her tampering made case-by-case appeals unworkable because the process would require far too many public defenders. The January SJC ruling pushed prosecutors toward dismissing Dookhan cases in bulk, but declined to wipe all defendants' slates clean. The court gave DAs in all seven districts an April 18 deadline to determine which convictions to dismiss and which to keep. The court made clear that prosecutors were to "reduce substantially" the number of defendants who might challenge their convictions because of Dookhan's crimes. It is not the "global" dismissal defense advocates sought, but some said they were pleased that as many as 95 percent or more of Dookhan cases may be vacated. "Even the possibility that this might happen means that anyone who cares about criminal justice in Massachusetts ought to be paying attention to April 18," said Matthew Segal, legal director of the American Civil Liberties Union of Massachusetts, whose clients' lawsuit led to the SJC ruling. The court reserved the right in its ruling to dismiss additional cases if the prosecutors do not dismiss enough cases.........The unanswered questions are which convictions will remain in effect and whether individual Dookhan defendants with standing cases will appeal in court. According to one data analysis conducted by the ACLU of Massachusetts and cited by the SJC, a majority of Dookhan defendants were convicted on drug possession charges alone. Approximately 90 percent of convictions were misdemeanors or minor felonies for which defendants had already served their time, that data indicated. District attorneys say their top priority in reviewing cases is public safety, and they might try to preserve some convictions under non-felony charges in lower courts if that means they can keep a violent offender behind bars. But prosecutors face a tough evidentiary burden to keep convictions in any cases handled by Dookhan. For all undismissed cases, the district attorneys must certify they could prove the defendant's guilt without using evidence that was tainted by Dookhan's dubious testing or testimony. That would be particularly difficult for older cases in which drug samples were destroyed years ago, or cases where the defendant pleaded guilty only after receiving results from Dookhan's analysis. All defendants whose convictions remain in place must be notified by mid-May, under the SJC's order."