The UK Court of Appeal has forced a landowner to pay damages to his neighbour for encroachment by the “pernicious weed” Japanese knotweed. (See Network Rail Infrastructure Ltd v Williams & Anor [2018] EWCA Civ 1514) Knotweed poses special challenges for landowners, as it can quickly establish and dominate in new areas, its root system can stretch seven metres and it is known to undermine structures.

The judgment, delivered on 3 July 2018, is particularly interesting because the claimants were unable to prove any physical damage to their property; they won because the knotweed interfered with “quiet enjoyment” of their properties.

Why? Knotweed is a “natural hazard” that affects an owner's ability to fully use and enjoy her land. It carries the risk of future physical damage to buildings, structures and installations on the land. Its presence, and indeed the mere presence of its rhizomes, imposes an immediate burden on the owner of the land in terms of an increased difficulty in the ability to develop, and in the cost of developing, the land, should the owner wish to do so. In the UK, it can affect a lender’s willingness to fund the purchase of affected property.

This claim was brought against Network Rail, the owner and operator of railway infrastructure throughout Great Britain. The most senior judge in the UK Court of Appeal had little sympathy for the breadth of the rail network. Network Rail was aware of the knotweed from 2008, was aware it was a serious problem from 2012 and received complaints from these particular landowners in 2013. The Court was not impressed with the treatment plan, which had been sporadic (only three spray treatments in five years), or with the suggestion that knotweed is common in the general area.

There have been several recent successful claims in the UK, including one where the defendant was liable for a 10% reduction to the value of the claimants' STG£500,000 house for allowing Japanese knotweed to spread.

We can expect similar claims in Ireland, where claimants, to establish a burden to act, will rely on the fact the European Communities (Birds and Habitats) Regulations 2011 made it an offence to plant, disperse, allow or cause to disperse, spread or grow specified invasive species, including Japanese knotweed.

Those responsible for transport, water, gas and other linear infrastructure projects are particularly exposed, given the opportunity for knotweed transfer over long distances. This UK Court of Appeal decision presents a timely reminder to revisit existing knowledge about knotweed infestation, to increase attention to those areas where complaints have been made and to document carefully the implementation of prudent treatment plans.

If you have queries about how this judgment might affect you, please contact Brendan Slattery, Michelle Doyle or your usual contact within McCann FitzGerald.