The expression "harmful weeds" is often and rather unfortunately used as a substitute for the legal term "injurious weeds" in various guidance documents, official publications, and online resources. This substitution could appear entirely harmless but it is clear that it is not. It involves a misrepresentation of the law and has directly led to widespread public misunderstanding of ragwort law and the law on other plants listed under the Weeds Act 1959.
The Weeds Act 1959 refers throughout to "injurious weeds." This is not just casual usage of a phrase. It is in reality a term of art in the law with a specific legal meaning. This is rooted in centuries of parliamentary usage and there is a resource on this website allowing you to examine every use of the word across 200 years of parliamentary debate. The word "injurious" in this context means damaging to the interests of agriculture, and this is originally in the context of 1920s agriculture before the biodiversity crisis, by spreading onto productive land and causing problems with the growing of crops. It has absolutely nothing to do with toxicity, danger to health, or any risk of poisoning.
The word "harmful" has multiple meanings in a way that the word "injurious" does not. In normal everyday speech, "harmful" most easily suggests something that is a danger to health or something that can hurt you if you touch it, eat it, or go near it. Indeed you will actually see people on social media telling people that ragwort is poisonous — not venomous, it won't jump out and bite you like a snake. When various official documents from councils and suchlike put "harmful weeds" in place of "injurious weeds," people reading them will naturally tend to think, incorrectly, that this means the plants are dangerous to animals or people. This is a problem as it is a significant and unfortunately consequential distortion of what the text of the legislation actually says.
It is important because the Weeds Act 1959 places no duty on landowners to protect the public or animals from toxic plants. It is designed only to be concerned with the agricultural spread of certain weeds onto neighbouring land. The occupier of land is not in breach of the Act simply because there is some ragwort growing on their land. The Act only comes into effect when the relevant authority serves what is actually a rare notice requiring action.
The technical and legalistic word "injurious" has a long and very consistent history in the context of parliamentary debate. The parliamentary record in the UK and many English-speaking nations is called Hansard, after the pressman Thomas Curson Hansard who first started publishing his own detailed accounts of parliamentary debates. A systematic survey published on this website covering over 200 years of Hansard from 1803 onwards shows the word used repeatedly in contexts of economic and agricultural damage such as to trade, to commerce, to farming, to the rights of landowners. The survey covers 2,097 recorded parliamentary uses including the adverbial form "injuriously" across more than two centuries. It contains no examples of "injurious" being used to mean toxic or dangerous to health in any agricultural or legislative context.
This historical evidence is available in full in the index of parliamentary usage by year. It demonstrates clearly that the meaning of "injurious" was well understood by legislators and that the Weeds Act 1959 uses the word in precisely its established sense.
Of the 2,097 recorded uses, 128, around six per cent, appear in connection with health, in phrases such as "injurious to health" or "injurious to the health of the population." This statistic might appear to some to support the idea that "injurious" can carry a toxic or poisonous meaning. The actual text of usage in the parliamentary record shows clearly and definitively that this is not the case.
What we see from the Hansard text is that in every single case the word is used in exactly the same sense as in all other parliamentary uses. It means damaging or detrimental. "Injurious to health" means damaging to health. It is the same word doing the same job, simply applied to a different object.
The parliamentary record itself gives us very good proof of this. In a 1928 Lords debate on petroleum spirit, the wording under discussion used the phrase "dangerous or injurious to health." Lord Desborough quoted this exact wording directly on two separate occasions during the same debate. If the word "injurious" already meant dangerous or toxic, this phrasing would be unnecessary and there would be no need to use both words. The fact that parliamentarians deemed it necessary to use both words together illustrates clearly that they understood them to mean different things. "Dangerous" covered something like acute risk while "injurious" covered damaging effects — in this case the occupational health consequences of regular exposure for garage workers and others coming into contact with petroleum spirit in the course of their work. That is damage to health over time, not poisoning.
Lord Strabolgi's observation in 1938 that many cases coming before the courts were "injurious to health" is in the same vein. It carries the same meaning — detrimental, damaging, causing harm. It does not imply toxic or poisonous.
This distinction is supremely important in this matter. "Damaging to health" and "toxic" or "poisonous" are not the same thing. A noisy factory may be injurious to the health of nearby residents or overcrowded housing may be injurious to the health of its occupants. It is obvious that none of these things are toxic or poisonous. The word "injurious" describes the relationship between a cause and its effect. It very clearly says nothing about the mechanisms involved and of course it says nothing at all relating to toxicology.
Where parliament wished to express the meaning of toxic it used the word "dangerous" alongside "injurious." These are distinct concepts requiring distinctly different expression. In 2,097 recorded parliamentary uses covering a long period of more than two centuries, "injurious" is never once used as an alternative expression for toxic, poisonous, or dangerous to touch or consume. Hansard is consistent about this throughout.
The truth of this matter is that in law words mean what they were intended to mean by parliament when the laws concerned were written, and these meanings are judged by their established usage. Using "harmful weeds" as a substitute for "injurious weeds," even if the intent is to use simpler words, is still a clear misrepresentation. The proper way to handle this is to use the legal phrase and to accurately describe its meaning as it is in law, where "injurious" means damaging to something in an abstract sense rather than a concrete expression of poisonous nature.
See also: Injurious weeds and the law and the index of parliamentary usage of "injurious" by year.