None of the tens of thousands of defendants convicted of drug crimes after a chemist at a Jamaica Plain lab tampered with evidence should face the possibility of a harsher sentence if they seek a new trial, the American Civil Liberties Union argued Thursday.
The case before the Supreme Judicial Court involves Annie Dookhan, the drug lab chemist who was sentenced in 2013 to at least three years in prison after admitting she faked test results.
ACLU lawyer Matthew Segal said many ‘‘Dookhan defendants’’ are afraid of asking a judge to vacate their guilty pleas in order to seek a new trial because under state law, they can be prosecuted for crimes that had been dropped when they entered their original plea deal.
‘‘They are afraid, and with good reason,’’ said Segal, the legal director for the ACLU of Massachusetts.
The ACLU estimates that over 40,000 convictions are linked with the drug lab scandal.
But prosecutors suggested that the number that would ultimately seek to have their convictions overturned is much lower.
Lawyers for the Suffolk and Essex district attorneys’ offices opposed the ACLU’s request, saying it is hypothetical and not yet appropriate for review by the court.
They also rejected the argument that prosecutors would seek to ‘‘punish’’ defendants who seek new trials.
The Committee for Public Counsel Services, which oversees public defenders in Massachusetts, said prosecutors have delayed in providing basic information to help identify and reach out to affected convicts, a notion the district attorney’s offices disputed.
‘‘We’re two and a half years out from this, and we’re virtually no closer than we were when this scandal broke to actually being able to provide relief to those that had their rights violated,’’ said Benjamin Keehn, the committee’s lawyer.
‘‘We don’t know,” he said. “It could be 40,000 convictions, or 30,000 or 20,000.’’