A "fixed form" can be as little as a dated and signed copy of a work tucked away in a drawer, or a single performance in front of others, even a nonpaying audience. Copyright protection includes both published and unpublished works.
Copyright protection means just that: No one has the right to copy the work without the permission of the copyright holder. This permission is typically only granted in exchange for a monetary payment. In the case of plays, performing the work constitutes copying it. Many playwrights assign their copyrights to an agent or agency skilled in enforcing copyright protections.
Agencies for theatrical works are known as publisher-leasing agents. The two largest publisher-leasing agencies in the United States are Samuel French, Inc. and Dramatist Play Service. In the case of musicals, scores may be assigned separately to either BMI or ASCAP, the two agencies most used to enforcing copyright protection of musical works. While the Internet has made life harder for BMI and ASCAP due to file-sharing, it also has made life much easier for Samuel French and DPS. A single mention of an unlicensed performance published online virtually ensures the producer will be contacted by the publisher-leasing agency charged with enforcing copyright protection on behalf of the playwright.
The consequences of performing a play without permission fall upon the producer. These consequences include cease-and-desist orders prohibiting continued performances. Failure to comply with such an order is punishable by a contempt citation, which can take the form of a fine and/or incarceration. In addition to cease-and-desist orders, the copyright holder can and likely will vigorously pursue civil remedies. In addition to the recovery of the funds usually charged for use of the work -- which varies according to actors' salaries, theater size and ticket price -- legal costs and damages may be sought.
The "work product" exception applies to work created by an employee at the direction of an employer. TV writers, for example, generally have no copyright protection for their work, the copyright being held by the writer's employer. This arrangement can be set aside by contractual agreement between the writer and the producer. Residuals, which are payments to writers for repeat broadcasts of their work, are separate contractual matters not related to copyright. The work product exception may apply to plays written under commission.