Mr Justice Turner is being asked to decide whether keepers at a Kent zoo park, where three have been killed by tigers, should be allowed to put their lives at risk by entering the tiger enclosures.

The case, concerning Howletts Zoo near Canterbury, which is owned by John Aspinall, is well dressed in legal argument. A ban on keepers entering the enclosure was imposed by Canterbury City Council after the third keeper, 32-year-old Trevor Smith, was killed by a tiger in November 1994. It was lifted by an Industrial tribunal, which allowed an appeal by Aspinall at the beginning of this year. Now the council has gone to court and is asking for the tribunal's decision to be overturned.

In the High Court, Hugh Carlisle QC argued that the tribunal's approach to the duty imposed on zoo owners by the 1974 Safety at Work Act was to ensure the safety of workers.

He said the tribunal was wrong to take the view that this duty was "subject to the idiosyncrasy of the particular business." It was argued for the council that the tribunal also failed to have proper regard to codes laid down by the Federation of Zoological Gardens of Great Britain.

Mr Carlisle said that the council's view was that keepers should not venture into cages with tigers unless the animals were "very young or immobilised".

For Howletts, John Taylor QC argued that the industrial tribunal had been entitled to lift the ban. He said it had been correct in the way it had approached its assessment of whether duties under the 1974 Safety at Work Act had been complied with. There had to be an appreciation on the part of a tribunal dealing with such an issue of the context.

"Without that there could be no rational decision as to whether what was being done was being done safely or not."