The council was ordered to pay £25,000 damages to Clifford Jordan who had his turf torn up, fences demolished and trees knocked down during the works.
Norfolk had no power to lay the drain across Mr Jordan's land and was guilty of trespass, said Deputy Judge Andrew Park QC. The council came out of the case 'very badly'.
From the beginning it had had grave doubts about its powers in this matter but 'tried very hard to stop the truth emerging', said Deputy Judge Park.
The council had 'attempted to conceal' the fact that the drain would be used to remove surface waste from the private supermarket site as well as from a public feed road, said the judge.