After rejecting a half-billion-dollar settlement, Washington Attorney General Bob Ferguson on Monday took the state’s case against the nation’s three biggest drug distributors to trial, saying they must be held accountable for their role in the nation’s opioid epidemic.

The Democrat delivered part of the opening statement in King County Superior Court himself, calling the case possibly the most significant public health lawsuit his agency had ever filed.

“These companies knew what would happen if they failed to meet their duties,” Ferguson told Judge Michael Ramsey Scott. “We know they were aware of the harms flowing from their conduct because in private correspondence, company executives mocked individuals suffering the painful effects of opioid dependence. ... They displayed a callous disregard for the communities and people who bear the impact of their greed.”

But Ferguson’s legal strategy isn’t without risk, as a loss by three California counties in a similar case this month — and an Oklahoma Supreme Court decision overturning a $465 million judgment against drug manufacturer Johnson & Johnson — demonstrates.

Orange County Superior Court Judge Peter Wilson issued a tentative ruling Nov. 1 that the counties, plus the city of Oakland, had not proven the pharmaceutical companies used deceptive marketing to increase unnecessary opioid prescriptions and create a public nuisance. The Oklahoma ruling said a lower court wrongly interpreted the state’s public nuisance law.

In an email, Ferguson stressed that the relevant Washington laws differ and called the cases “apples and oranges.”

Public nuisance claims are at the heart of some 3,000 lawsuits brought by state and local governments against drugmakers, distribution companies and pharmacies. Washington is the first by a state against drug distribution companies to go to trial. Ferguson is claiming public nuisance and violations of state consumer protection law.