The concept of a shop right is not found in any law. Instead, it is a judicial creation that grew out of equitable principles. Because of this, shop rights are fact-specific. When determining whether a shop right exists in a particular situation, a court will consider several factors to determine whether equity and fairness should entitle the employer to use the invention without paying a royalty. These factors include “the contractual nature of the relationship between employer and employee, whether the employee consented to the employer’s use of the invention, and whether the employee induced, acquiesced in, or assisted the employer in the use of the invention.” U.S. v. Dubilier Condenser Corp., 289 U.S. 178 (1933).