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Common law private nuisance cases involving the invasive non-native plant, Japanese knotweed (JK), received a considerable amount of attention in the county court in 2017 and 2018. In the joined cases of Williams v Network Rail Infrastructure Limited (B20YX969) and Waistell v Network Rail Infrastructure Ltd  UK CC, Mr Recorder Grubb, sitting in Cardiff County Court, awarded damages to the claimants for loss of amenity on the basis that JK on the defendant’s land had diminished the value of the claimants’ land by reason of it rendering the claimants’ land less acceptable as security for mortgage lending, even in the event of the JK on the defendant’s land having been treated (see Article, Japanese knotweed nuisance in the light of Waistell and Smith v Line).
In Smith and another v Line (CTR00216) WL 09565854 (6 November 2017), another case which attracted considerable news media interest, His Honour Judge Carr, sitting in Truro County Court, agreed with Mr Recorder Grubb’s analysis and granted an injunction requiring the defendant to treat the JK on her land.
Loss of amenity: diminution in value not sufﬁ cient in and of itself
The defendant to the Cardiff County Court claims, Network Rail, appealed and the Court of Appeal in its keenly anticipated decision in Network Rail Infrastructure Ltd v Williams and another  EWCA Civ 1514, while upholding the decision on other grounds, applied the judicial secateurs to the reasoning of Mr Recorder Grubb.
In the view of the Master of the Rolls, Sir Terence Etherton, (with whom the other judges, Sharp and Leggatt LJJ, agreed), the decision under appeal was wrong in principle in that it unjustiﬁably extended the tort of nuisance to a claim for pure economic loss. As such, it constituted a:
“radical reformulation of the purpose and scope of the tort rather than an incremental development… by way of analogy.”
The Master of the Rolls disagreed with the Recorder’s view that the impact on the value of the claimants’ land of the presence of the JK on the neighbouring land (that is, the claimant’s inability to sell it for full value because of lender caution) was an actionable nuisance. He held that the purpose of the tort of nuisance was “not to protect the value of property as an investment or a ﬁ nancial asset”, but rather “to protect the owner of land (or a person entitled to exclusive possession) in their use and enjoyment of the land as such as a facet of the right of ownership or right to exclusive possession”.
The Court considered that the stigma cases relied on by the respondent claimants (Thompson-Schwab v Costaki  1 WLR 335 (prostitution) and Laws v Florinplace (sex shop)) did not support the argument that diminution in value could, in and of itself, constitute an interference with a claimant’s use and enjoyment of his or her land.
The effect of the Court of Appeal’s decision is that A does not have a cause of action in nuisance where B does something or omits to do something on B’s land that leads merely to a reduction in the value of A’s land. It remains necessary to establish that B has interfered with the “comfortable and convenient enjoyment of” A’s land.
On that test, the mere presence of JK on neighbouring land does not cut the mustard. However, perhaps if B were to lay out a row of Titan Arums (Corpse Flowers: supposedly the smelliest plants in the world) or plant bulbs in such a way that they grew up to spell out an offensive message to A, then A might still be able to establish nuisance.
Encroachment: the need for damage
The loss of amenity argument had been advanced in Williams and Waistell as well as in Smith v Line as an alternative to a claim based on the encroachment of JK from the defendants’ land onto the claimants’ land.
The encroachment claims had been rejected in the County Court because the encroachment had not caused physical damage to the claimants’ land. In the Network Rail cases there was, for example, no evidence of damage to buildings or foundations, no evidence that the load-bearing qualities of the soil had been adversely affected by dehydration and no evidence of a change in soil structure (other than the presence of JK rhizomes).
The Court of Appeal, however, considered that the encroachment of JK onto the claimants’ land was a “classic example of interference with the amenity of the land”. The Master of the Rolls said:
“[JK] was rightly described by the Recorder… as a pernicious weed. It does not only carry 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 difﬁ culty in the ability to develop, and in the cost of developing the land, should the owner wish to do so. As the [2012 RICS ‘information paper’ on “Japanese Knotweed and Residential Property”] observed, any improvement or alteration of the property requiring the removal of contaminated soil would require disposal of the soil either on site or, more likely, off site by special, and probably expensive, procedures. For all those reasons, [JK] and its rhizomes can fairly be described, in the sense of the decided cases, as a “natural hazard”. They affect the owner’s ability fully to use and enjoy the land.”
The Court of Appeal held that JK infestation into a claimant’s soil was as much an interference with amenity as were the matters complained of in cases relied on by the claimants at ﬁ rst instance (both in Cardiff and Truro): dust ground into carpets (Hunter v Canary Wharf Ltd  AC 655 (per Pill LJ in the Court of Appeal at 676)), small amounts of plutonium mixed into soil (Blue Circle Industries Plc v Ministry of Defence  Ch 289) and deposition of excessive silt (Jan de Nul (UK) Ltd v AXA Royale Belge SA  EWCA Civ 209). Network Rail was consequently liable in nuisance in the light of:
To that extent, it might be thought that there remained some distinction between encroachment by JK (or other plants sharing its pernicious characteristics) and encroachment by the branches or roots of trees, where cases such as Lemmon v Webb  A.C. 1 or Delaware Mansions v Westminster City Council  UKHL 55 suggest a need to prove physical damage. However, such distinction is blurred in the light of the Court of Appeal observing that a mandatory quia timet injunction might be obtained in a root/branch case where amenity has been diminished even before physical damage has occurred and, moreover, that the imminence of damage (for the purposes of obtaining such an injunction) is less important than the probability and gravity of the feared damage.
Having found that Network Rail was liable in nuisance, the Court of Appeal declined to interfere with Mr Recorder Grubb’s award of damages because:
The decision therefore gives no guidance as to the proper quantiﬁ cation of damages in such cases. Where development of the land on which the JK has encroached is in prospect, then this may be a simple question of valuation. However, given that evidence of development potential seems not even to be required for the claim to be made out, this will not be simple in cases where development is unlikely.
Nor, notwithstanding that the JK had been present for over 50 years, does this decision give any guidance as to the potential impact of the Limitation Act 1980 on the quantiﬁ cation of damage.
The claimants had not pressed at trial for an injunction and the Court of Appeal did not therefore consider whether these particular claimants would have been entitled to injunctive relief. However, there is support for the decision in Smith v Line from the Master of the Rolls’ statement that:
“I see no reason why, in appropriate circumstances, as in the present case, a claimant should not be able to obtain a ﬁ nal mandatory injunction where the amenity value of the land is diminished by the presence of roots even though there has not yet been any physical damage.”
The Court of Appeal restated the principles of the tort of nuisance as involving either action or inaction constituting a violation of property rights which ought not be rigidly categorised but might be exempliﬁ ed by:
Interference with a claimant’s quiet enjoyment of his or her land and that the unifying principle was reasonableness between neighbours.
Importantly, it went on to caution against the proposition that physical damage was a necessary element of nuisance because it was “not entirely correct” and the concept of damage in this context was “highly elastic”. Furthermore, the court stated that, in cases of interference with amenity, it was well established that physical damage was not necessary.
So, in summary:
John Clargo acted for Mr and Mrs Smith in Smith v Line.
This article was first published on Practical Law UK.
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