A more thorough explanation:

The three-step test is a legal analysis used to determine if the use of a protected work is considered an infringement under the TRIPs and Berne Convention. The test involves three steps:

1. Is the use of the protected work limited to special cases?
2. Does the use of the protected work conflict with the owner's normal exploitation of the work?
3. Does the use of the protected work unreasonably prejudice the legitimate interests of the owner?

This test is similar to the fair-use doctrine in U.S. law.

Let's say a musician wants to use a sample from another artist's song in their own music. They would need to apply the three-step test to determine if their use of the sample is considered an infringement.

1. Is the use of the sample limited to special cases? In this case, it may be argued that using a sample is a common practice in the music industry, so it may not be limited to special cases.
2. Does the use of the sample conflict with the owner's normal exploitation of the work? If the sample is used in a way that competes with the original song, it may be considered a conflict.
3. Does the use of the sample unreasonably prejudice the legitimate interests of the owner? If the use of the sample negatively impacts the original artist's ability to profit from their work, it may be considered unreasonable prejudice.

By applying the three-step test, the musician can determine if their use of the sample is considered an infringement or not.