Not necessarily. You could certainly have some quantifiable metric. For example, you could draw the line at, say, 80% of the works on offer. In this case, that

Not necessarily. You could certainly have some quantifiable metric. For example, you could draw the line at, say, 80% of the works on offer. In this case, that wouldn't be necessary. There may be a fine line somewhere where you could argue that a piece of software does or does not have infringement as its primary purpose. PopcornTime is not close to that line.