Common carrier doctrine had established that businesses offering services to the general public had obligations toward that public that private businesses did not. They could not arbitrarily refuse service; they were required to carry all comers who met reasonable standards. The question the Jennings case raised — and that Rockwell’s instruction answered at the trial court level — was whether race was a legitimate ground for exclusion under this doctrine.
Rockwell said no, with the conditional framing about sobriety, behavior, and disease that marked his instruction as a product of its era. In saying no, he extended the logic of common carrier obligation to include Black passengers — at least those who met the stated conditions. This was not a formal appellate ruling that would bind courts throughout New York; it was a trial court instruction that other courts could choose to follow or not.
In the years following the verdict, the practical significance of the Rockwell instruction was its use in organizing and in subsequent litigation as a statement of what the law was. The Legal Rights Association could point to it when arguing with other transit companies about their obligations. Attorneys in subsequent cases could cite it as an example of how a New York court had understood the law. It did not create binding precedent, but it created persuasive precedent.
The eventual statutory prohibition on transit discrimination in New York, whenever precisely it came, reflected the accumulation of this legal reasoning and the political pressure the organizing campaign had generated. Statutory law is more durable than trial court instructions; it applies uniformly and can be enforced without requiring a new lawsuit for each violation. The path from the Rockwell instruction to a statutory rule was indirect and took years, but the instruction was one of the legal building blocks along the way.