Preventative anticipation ... is a willingness to take action in advance of scientific proof of evidence of the need for the proposed action on the grounds that further delay will prove ultimately most costly to society and nature, and, in the longer term, selfish and unfair to future generations.

Safegaurding of ecological space ... or environmental room for manoeuvre as a recognition that margins of tolerance should not even be approached, let alone breached. This is sometimes known as widening the assimilative capacity of natural systems by deliberately holding back from possible but undesirable resource use.

Proportionality of response ... or cost-effectiveness of margins of error to show that the selected degree of restraint is not unduly costly. This introduces a bias to conventional cost benefit analysis to include a weighting function of ignorance, and for the likely greater dangers for future generations if life support capacities are undermined when such risks could consciously be avoided.

Duty of care ... or onus of proof on those who propose change: this raises profound questions over the degree of freedom to take calculated risks, thereby to innovate, and to compensate for possible losses by building in ameliorative measures. Formal duties of environmental care, coupled to an extension of strict liability for any damage, no matter how unanticipated, could throttle invention, imagination and growth. Alternatively, when creatively deployed such strictures could encourage imagination and creativity in technology, economic valuation, technological advance and unusual forms of ameliorative compensation. Hence the concept of proportionality can be regarded either as a deadweight or a touchstone for the visionary.

Promoting the cause of intrinsic natural rights ... where the legal notion of ecological harm is being widened to include the need to allow natural processes to function in such a manner as to maintain the essential support for all life on earth. The application of ecological buffers in future management gives a practical emphasis to the thorny ethical concept of intrinsic natural rights.

Paying for past ecological debt ... where precaution is essentially forward looking but there are those who recognize that in the application of care, burden sharing, ecologically buffered cost effectiveness and shifting the burden of proof, there ought to be a penalty for not being cautious or caring in the past. This suggests that those who have created a large ecological burden already should be more "precautious" than those whose ecological footprints have to date been lighter. In a sense this is precaution put into reverse: compensating for past errors of judgment based on ignorance or an unwillingness to shoulder an unclearly stated sense of responsibility for the future. This element of the principle is still embryonic in law and practice, but the notion of "common but differentiated responsibility" enshrined in the UN Framework Convention on Climate Change, and the concept of conducting precaution "according to capabilities" as laid down in principle 15 of the Rio Declaration reflect to some extent these ideas.