The 1999 National Competition Policy Review of Ag & Vet Chemical legislation recommended, inter alia, that registrants no longer be required to prove ‘APPROPRIATE’ levels of efficacy of their products but only that the claims on product labels be ‘TRUE’. ‘Appropriate’ efficacy standards amount to market regulation, limiting economic competition from formulations with lower efficacies. Cheaper formulations with lower efficacies are excluded from the marketplace by such standards. Unanswered is the question of what ‘TRUTH’ on a label means in practical terms. Flexibility in dose rates and guidance with usage information is not always well-stated on herbicide labels. There is considerable evidence that efficacy of herbicide varies with dose and with environmental or growth conditions. Under favourable conditions at a given site, a low rate of herbicide will kill most of the target weeds. Under less favourable conditions at the same site, a high rate may be required. Labels could take variations in efficacy into account by indicating observed results for a range of environmental conditions at different dose rates. This is illustrated with examples of herbicide performance and analogies from another industry in which explicit performance information is absolutely required. This paper raises the question of reforms towards providing ‘the whole truth’ in herbicide labelling, to provide users with guidance on when they might adjust doses to specific environmental and growth conditions.