A judge is to rule on a challenge against a coroner's decision not to call evidence from pupils who had contact with the schoolboy killer of teacher Ann Maguire immediately before the murder.
Mrs Maguire's husband Don, children and nephews want Mr Justice Holroyde to order the decision taken by assistant West Yorkshire coroner Kevin McLoughlin to be reconsidered.
An inquest into Mrs Maguire's death is due to take place before a jury at Wakefield Coroner's Court in November.
The 61-year-old teacher was stabbed in the back by 15-year-old Will Cornick as she taught a Spanish class at Corpus Christi Catholic College in Leeds in April 2014.
Cornick was later sentenced to life with a minimum term of 20 years.
Last month counsel Nick Armstrong told the judge, who will give his decision at London's High Court on Monday, the family were anxious "all the lessons that can be learned from this enormous tragedy are learned".
Mr Armstrong said that over the three hours before the murder, Cornick told other students what he intended to do, and showed a number of them the knife - yet no report to a member of staff was made, at least until it was too late.
The coroner said those students - now adults - were "potentially vulnerable" and were not to be re-approached, with the result that only transcripts of their interviews with police at the time would be adduced.
Mr Armstrong said: "His decision was a blanket one based on limited and generic evidence about vulnerability generally."
This approach was unlawful, said counsel.
Cathryn McGahey QC, for the assistant coroner, said the decision was one that was lawfully open to him.
Leeds City Council had said the facts regarding the morning of the incident were already clear and required no duplication of inquiry.
"The key issue was the usefulness of the evidence that these students could give.
"The coroner was entitled to reach the view that the benefit of calling the students would be limited."
Most of the students told the police they had not taken Cornick's threats seriously and the transcripts of their contemporaneous interviews would be available.
The evidence of teaching staff, who had experience of the attitudes of hundreds of students of varying ages, was likely to be far more reliable and useful than that of a small number of former students.