Impinge, meaning (1) to collide or strike, or (2) to encroach, is usually followed by on or upon. In the second sense, in which the word is most common today, impinge is an intransitive verb, so it can’t have a direct object (that is, it can’t act directly on something and must have the on or upon to intervene). For example, you might impinge on something’s privacy, but you don’t impinge their privacy.
Impinge‘s near synonym infringe is both transitive and intransitive. As a transitive verb it means to violate or to break. For example, one might infringe the law by speeding on the highway. As an intransitive verb, it’s synonymous with impinge—that is, it also means encroach—and likewise takes on or upon.
Good planning ensures that building types do not impinge on each other. [Financial Times]
Why do you want to impinge on a persons fantasy sports blog talk and tell them what’s acceptable to fantasize about and what isn’t? [Los Angeles Times]
But it said documents already obtained under FOI laws showed plain packaging would impinge on tobacco companies’ trademark rights. [Sydney Morning Herald]
The court can overrule legislation on budget issues and taxes only if they infringe basic rights to life and human dignity. [Montreal Gazette]
Vermont is appealing a decision that said the law infringes on free commercial speech. [USA Today]
Neither really wants to infringe the autonomy of universities. [Guardian]