Failure to control Japanese Knotweed is an actionable nuisance

In Williams v Network Rail Infrastructure Ltd (2017) the Cardiff County Court ruled that the defendant, Network Rail, had caused an actionable nuisance by failing to control Japanese Knotweed, which spread from its railway embankment to neighbouring homes.

Mr Williams and his neighbour Mr Waistell of Maesteg, Glamorgan, brought the claim against Network Rail arguing that the knotweed had spread into the foundations of their properties causing damage. They also argued that the presence of the knotweed on the defendant’s land was an interference with the quiet enjoyment of their land and also prevented them from selling their properties at their proper market value.

The railway embankment and path had been infested with knotweed for 50 years which had persistently spread to the surrounding properties. Japanese Knotweed is an invasive alien species which not only causes structural damage to buildings and threatens plant biodiversity but is also prohibitively expensive to eradicate.

Cardiff County Court found in favour of Mr Williams and his neighbour (“the Claimants”) stating that while no structural damage to the homes was actually proven, the knotweed had spread to beneath their homes and had affected the market value of the properties.

The main success of their case was the presence argument – that the presence of the knotweed on the railway embankment was effectively causing a blight on their land by interfering with their quiet enjoyment of it. They had demonstrated that the interference was reasonably foreseeable and that Network Rail had failed to take action.

Although the court fell short of ordering Network Rail to eradicate the knotweed from their own property, they were ordered to pay the Claimants’ cost of surveys, treatment programmes and insurance backed guarantees to remove the infestation from their properties. The Claimants were also awarded damages for the diminution in value of their homes and general damages for loss of amenity and interference with quiet enjoyment of their land.

Although this is a county court case, it is significant in determining that despite no physical damage actually being proven, the knotweed is an actionable nuisance due to the diminution in value it causes to neighbouring properties. The case was also notable as it said that since The Royal Institute of Chartered Surveyors published guidance in 2012 warning of the threat of Japanese knotweed, Network Rail was deemed to have constructive knowledge of the risk.

The case has particular implications for large landowners, such as Network Rail, trying to control invasive non-native species, particularly along railway lines, roads and rivers.