More than 20 families - including mother-of-five-Angela Drury - moved into Fermyn Woods, near Brigstock, in April this year.
And, on May 23, Judge Stephen Waine issued a possession order against the travellers who have sinced moved away from Fermyn Woods.
He also granted the department possession orders in respect of 30 other woodland areas within a 20-mile radius.
Today at London's Appeal Court, Ms Drury's QC, Mr Richard Drabble, attacked the possession order as a violation of legal principle.
Although he accepted the travellers had been trespassers at Fermyn Woods, he said there was no evidence that they had any intention to move from there onto other woodland covered by the possession order.
Judge Waine had, in effect, made a 'pre-emptive order' banning 'persons unknown' - 'whoever they may be' - from vaguely drawn areas of land for an indefinite period, Mr Drabble told the court.
That may have been 'administratively convenient', but it failed to meet the 'overriding objective' of fairness, added the QC, who said the case raised 'important issues of principle'.
In theory, he said, Judge Waine could have made possession orders covering all Forestry Commission land in England and Wales even though none of the travellers had ever been, or threatened to be, 'in possession' of those sites.
However, Mr John Hobson QC, for the department, said Judge Waine had been right to extend the possession order to cover the other 30 areas of woodland.
He said there was 'convincing evidence' of a tendency amongst travellers to occupy a piece of land, wait until the court orders them off, and then move to another plot nearby.
There was a 'h istory' of trespass on other Forestry Commission land in the area and Mr Hobson said the wide-ranging possession order was 'proportionate and reasonable'.
It would, he added, be 'oppressive' to expect landowners to go through the time and expense of launching individual court actions each time they were faced with trespassing travellers.
Observing that camping on Forestry Commission land is also a criminal offence under bye-laws, Mr Hobson said trespassers not only had an impact on the productive management of woodland but also the public's access and enjoyment of such areas.
The hearing before Lord Justice Ward, Lord Justice Mummery and Mr Justice Wilson, continues.
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