The ethics and standard-of-care witness in the negligence trial of two engineering firms connected to the 2015 Flint, Mich., water crisis said in three days of testimony that both firms failed to act to stop or limit the public danger despite having the knowledge and obligation to alert higher government authorities.

A potentially damaging witness seeks to avoid testifying against his company's own client.

Lockwood Andrews Newnam chief engineer details assurances that he claims were betrayed by Flint officials, leading to the city's water crisis.

Some view plan as modest improvement from 1991 rule, but critics say it weakens current protections.