The answer is a bit muddled because, unfortunately, international and domestic laws do not have a consistent definition of the precautionary principle or its various formulations. Generally, the weak precautionary principle states that governments should not delay regulation of an activity that poses a risk of substantial and irreversible harm even if scientific uncertainty remains over the degree or certainty of the risk. The strong precautionary principle takes the additional step of reversing the burden of proof – if someone wants to engage in an activity that poses such a risk, they have to affirmatively prove that their activity will not cause substantial and irreversible harm. Normally, of course, the burden of proving that an activity poses an unjustifiable risk would fall on the person or agency who files a lawsuit or administrative action to halt that activity. The strong precautionary principle flips that presumption and forces operators essentially to prove a negative proposition – i.e., their activities will not cause harm.
Not quite correct. While major stationary source usually trigger Clean Air Act permitting requirements under Title I by emitting criteria pollutants (under either the Prevention of Significant Deterioration program, or the non-attainment New Source Review program), other major sources can still require permits under other Title I requirements. The two major pathways relevant to climate intervention are: (1) the New Source Performance Standards (NSPS) and Existing Source Performance Standards (ESPS) programs, which can require controls on major emission sources of “pollutants” within certain industry categories named by EPA – even if those facilities don’t emit criteria air pollutants subject to NAAQS, and (2) the Prevention of Significant Deterioration program, which can require a major source to obtain a PSD permit in areas which are either in attainment, or for which EPA cannot determine whether they are in attainment. Because CO2 is a pollutant without a national ambient air quality standard and therefore EPA cannot determine whether any area in the U.S. meets NAAQS standards for CO2, EPA had previously argued that major CO2 emission sources must have a PSD permit. This stance, however, is seriously in question in light of the U.S. Supreme Court’s ruling in UARG v. EPA and the Trump Administration’s refusal to defend either the Tailoring Rule or the Clean Power Plan in court.
Ships operating in waters of the United States, including territorial seas, must obtain authorization for discharges of pollutants into those waters. EPA has relied on a general permit that applies to transportation ships operating in territorial waters, and other federal agencies have jurisdiction over discharges in the exclusive economic zone out to 200 miles (e.g., the Oil Pollution Act, the Ocean Dumping Act, and other federal laws governing energy production on offshore platforms). The more germane question – which we did discuss – is whether spraying sulfates into the air can constitute a discharge from a point source into waters of the United States if those particulates eventually settle onto those waters. The circuit courts have split on this particular issue, and the U.S. Supreme Court has heard oral argument on one case that will address a similar issue whether a facility discharges to groundwater (not a WOTUS) that eventually migrates into coastal waters.