"A person has a right to advance his own interests by lawful means even if the foreseeable consequence is to damage the interests of others."

ie a person has a *liberty* to do whatever they like even if it causes another foreseeable loss, just so long as they violate no (claim-)right of another.

 

"The existence of that right affords a just cause or excuse."

No. It isn't prima facie wrongful. There is nothing to excuse.

"Where, on the other hand, he seeks to advance his interests by unlawful means he has no such right."

No

How does the fact that I am behaving unlawfully (in the sense of committing a public wrong such as parking on double yellow lines) create a claim right in you that I do not do so? My lack of liberty to do X with respect to another doesn't mean you have a right against me that I do not do X

"The position is the same where the means used are lawful but the predominant intention of the defendant was to injure the claimant rather than to further some legitimate interest of his own. This is because in that case it cannot be an answer to say that he was simply exercising a legal right. He had no interest recognised by the law in exercising his legal right for the predominant purpose not of advancing his own interests but of injuring the claimant. In either case, there is no just cause or excuse for the combination."

If I exercise a liberty that I have with respect to you by parking in a particular place (eg I park on double yellow lines outside my house) there is nothing to excuse, with respect to you..

Hohfeld's Fundamental Legal Conceptions is, I think, the most important law journal article of the 20th Century. It is a bit depressing that our Supreme Court hasn't read it. 

R