In March, the US Supreme Court reinstated Tsarnaev's death penalty despite his attempts to have the capital sentence vacated by lower courts.
“Under the law, before a defendant may be put to death his appeal must first be decided,” Gardner said.
Gardner said Tsarnaev's case is back in the First Circuit Court of Appeals for resolution of the issues that were unresolved in the initial opinion of the court, however, it is unknown how long it will take for the case to be decided.
Media reports, citing analysts, have reported that it could take years for the appeals court to decide the case.
Tsarnaev attempted to avoid execution by arguing that his brother Tamerlan masterminded the bombing and pressured Dzhokhar to participate using his domineering nature, possible evidence of which he unsuccessfully tried to have included at trial.
An appeals court initially vacated Tsarnaev’s capital sentences on the grounds that a lower District Court made a mistake during jury selection by declining to ask about juror’s media exposure and excluding the possible evidence concerning Tamerlan’s alleged criminal history and personality. The US Supreme Court ruled that the District Court did not abuse its discretion in either situation.
The Boston Marathon bombing killed three people and injured hundreds of others. Tamerlan was killed by police while on the run on April 19, 2013, while Dzhokhar was arrested the following day and was sentenced to death by lethal injection in May 2015.