House Bill No. 6278 seeks to limit animal testing by manufacturers and contract testing facilities when alternative methods are available. It defines "alternative test methods" as those that either provide equivalent or superior scientific quality without using animals or minimize animal use and suffering when non-animal methods are not feasible. The bill allows exceptions for medical research related to human and animal diseases under certain conditions and clarifies that it does not prohibit testing methods that do not involve live vertebrate nonhuman animals. The provisions regarding animal testing will take effect on October 1, 2025.

In addition to the animal testing regulations, the bill mandates the gradual incorporation of biodiesel into diesel fuel sold at retail and used by state-operated vehicles, vessels, and construction equipment. Starting July 1, 2025, all diesel fuel must contain at least 5% biodiesel, increasing to 10% by July 1, 2027, and 20% by July 1, 2029. For state fleet vehicles, the biodiesel requirement is set at 5% by July 1, 2025, and 20% by July 1, 2027. The bill defines biodiesel as fuel derived from vegetable oils or animal fats that meets specific ASTM standards, emphasizing the use of pure biodiesel in fuel blends. The biodiesel provisions are effective immediately upon passage.