U.S. law does provide interesting examples of the intersection of positive and negative liberty, I don't personally agree with all of the decisions and some of the examples listed on that page are much, much more nuanced than they appear at face value including subsequent cases that clarified the meaning of those decisions. If we stay on topic with the relation of the two concepts of liberty to the decision by Dr. Seuss Enterprises LP to no longer publish 6 books because they “portray people in ways that are hurtful and wrong." and the subsequent decision by Ebay, Amazon, et al. to prevent resale of existing copies of those books then we get a really good example of another topic covered by Isaiah Berlin which is the abuse of positive liberty. Specifically, the demand for freedom from these entities to control the purchasing decisions of their customers with regard to materials that some supposedly rational authority has determined to be detrimental to some group of people (there are echoes of Roth v. United States here). The factors that make this a difficult problem are the near monopoly that Ebay and Amazon enjoy over online sellers and resellers and the fact that they act as intermediaries between those sellers and their customers.

My answer to this situation is similar to that of Justice Holmes, we need a free marketplace of ideas as well as a free marketplace of products. Breaking up monopolies in commerce and discourse goes a long way towards those goals.