Can I play a movie DVD at a friendly get-together in my home?

The short answer is yes.

We’ve all had friends over to watch movies or TV shows. And, as a general rule, that’s allowed by copyright law; copyright holders can’t prohibit you from marathoning Downton Abbey blu-rays with your best friend, even if they want to.

Copyright holders can, however, authorize (and prohibit) “public performances” of their copyrighted work. The real question is how big a gathering has to be before it’s considered “public.” Small to mid-sized social gatherings don’t generally make the cut because they’re not open to the public at large—in other words, strangers can’t walk in and plop down for a showing. However, if you threw a giant, open-invitation event attended mostly by strangers, you may have a problem.

Long answer: It depends on how big and open your party is.

Section 106 of the Copyright Act grants copyright holders the exclusive right to perform their works publicly. However, the “definitions” section of the statute (17 USC § 101) goes out of its way to say that most kinds of informal social gatherings are not “public” for the purposes of the statute. It specifically limits public performances to instances where the work is “perform[ed] or display[ed][…]at a place open to the public or at any place where a substantial number of persons outside of a normal circle of family and its social acquaintances is gathered.”

Obviously, the wording of the definition creates some ambiguity, and it’s easier to discuss it in terms of obvious examples. Playing National Lampoon’s Christmas Vacation in your living room for your cousins after Christmas dinner is obviously not a public performance; putting it on the Jumbotron at Madison Square Garden during a Knicks halftime show obviously is. Playing a movie on a TV in a store window, where members of the public can walk up and watch, counts as a public performance; so does putting on a DVD in the corner of a bar. Lots of cases are harder to classify. For instance, screening movies at a fraternity party may or may not count as “public performances.”