If these improvements would have taken place anyway, using them to offset biodiversity losses jeopardises the equivalence of an exchange. Conservation measures already required by law, such as noxious weed control, may be required even in the absence of offsets programmes, so allowing them to contribute to an offset overstates their actual contribution to conservation. The principle of ensuring that offsets comprise demonstrably new contributions to conservation is known as additionality (ICF GHK and BIO Intelligence Service, 2013). In the Netherlands, for example, the additionality of biodiversity offsets is a legal requirement under the Dutch Nature Conservation Act (de Bie and van Dessel, 2011) and in England, the Guiding Principles for Biodiversity Offsetting state that “offsets should not being used to deliver something that would have happened anyway.”