A judge was wrong to consider "a novel standalone claim" about the reliability of mobile phone tracking evidence in granting a new trial for a man whose murder conviction was re-examined in the popular Serial podcast, the Maryland attorney general's office said.
The podcast attracted millions of listeners who became armchair detectives as the series analysed the case of Adnan Syed for weeks in the winter of 2014.
Appealing against the decision to retry Syed, lawyers for the state contend that retired Baltimore Circuit Court Judge Martin Welch should not have ruled that his initial lawyers were constitutionally deficient because they failed to bring into evidence a warning from AT&T.
The cover sheet says: "Outgoing calls only are reliable for location status. Any incoming calls will NOT be considered reliable information for location." The first three words - "Outgoing calls only" - are underlined in the fax AT&T sent to Baltimore police.
Defence lawyers said prosecutors improperly used unreliable tower data on incoming calls to place Syed's phone near the burial site of his former high school girlfriend, Hae Min Lee, who was killed in 1999.
Judge Welch agreed, ruling that Syed's lawyer provided "ineffective assistance for the failure to cross-examine the state's cell tower expert about the reliability of cell tower location evidence".
In its appeal filed on Monday, the state counters that Syed's trial lawyer, Cristina Gutierrez, "was far from ineffective in her challenge of the state's cellphone evidence".
"For one thing, there is no consensus among experts in the forensic community that Syed's interpretation of the fax cover sheet is valid," wrote Thiru Vignarajah, a deputy attorney general.
"Where one expert concludes the disclaimer does not apply, another finds it does, and yet a third opines it is ambiguous, trial counsel cannot be declared ineffective for a sustained and vigorous cross examination that does not incorporate an uncertain line of attack."
The state also argued that Syed waived his right to raise the issue about the cross-examination failure now because he should have raised it in a prior proceeding.
But the judge ruled that Syed did not "intelligently or knowingly" waive his right, noting that he never completed his high school degree.
Syed's lawyers also argued that he deserves a retrial because his original lawyer did not contact Asia McClain Chapman, an alibi witness who swore in an affidavit that she saw Syed at the Woodlawn library at about the same time prosecutors say Ms Lee was murdered.
Judge Welch disagreed with the defence on that point. He also disagreed that prosecutors breached their duty by withholding exculpatory evidence.
But the attorney general's office says the judge was wrong to include arguments about the cover sheet in reopened legal proceedings that were supposed to be predicated on Chapman's newly available affidavit.
"Maryland's courts have imposed few limits on what qualifies as in the 'interest of justice,' but limits remain," wrote Vignarajah.