Convicted killer David Harold Eastman has threatened to have the Office of ACT Director of Public Prosecutions declared a vexatious litigant. Eastman - whose life sentence for the 1989 murder of ACT police chief Colin Stanley Winchester could be quashed after a recent inquiry - warned he could launch High Court action if a Canberra court allowed the DPP to make submissions on his bid for freedom. But the DPP also threatened High Court action if the full bench of the ACT Supreme Court did not allow it to be heard on whether Eastman's conviction should be overturned. Lgeal pundits now fear the matter could splinter into a number of separate matters, potentially delaying the final resolution of Eastman's fate by months. The full bench last week called for submissions on whether to follow a recommendation to quash Eastman's conviction, to do nothing, or to order a retrial. The court also asked whether it would be acting with judicial or administrative power. At a hearing on Tuesday, Eastman told the judges they had a "crystal clear" statutory duty to make a decision on his freedom based on a report by Acting Justice Brian Martin. Eastman said the judges could not ask for further submissions and had contravened the law in doing so. "You have to do this job on your own. You cannot ask for or receive submissions," Eastman told the court. "We don't need a lawyers-fest of QC's putting submissions to you. "The court should not be diverted into playing the DPP's game." Eastman warned the DPP would drag the matter into a "legal morass" and its conduct bordered on vexatious. Eastman threatened to seek prerogative relief in the High Court if the Canberra court did not revoke the invitation to receive submissions. The High Court could issue a prerogative writ directing the court to follow a certain course. But Justice Steven Rares told Eastman the court's job was to make an order about his conviction, not about the report. The judge assured the purpose of the proceedings were to determine the court's jurisdiction to make a decision. "We're not seeking to undermine the process," Justice Rares said. "We're seeking to understand what the process is. What the jurisdiction we're exercising is. "The first duty of the court is to determine jurisdiction and [that is] what we're doing." Counsel for the DPP, Tim Game SC, foreshadowed a challenge if the court did not allow it to join proceedings. He said the DPP would issue notices under the Commonwealth Judiciary Act to the Commonwealth and state attorneys-general. The notices would inform the ministers that the court would consider a matter regarding the Commonwealth constitution so that they could decide whether they ought to intervene in the case. Justice Rares granted the DPP leave to appear on the issue of jurisdiction. He also ordered the DPP to file fresh proceedings seeking a declaration on the construction of the ACT Crimes ACT. The DPP was also granted leave to serve the notices under the Commonwealth Judiciary Act to Australian attorneys-general. The matter will reappear before court later in June.