An "out-law strike", also known as a wildcat strike, is an unauthorized work stoppage initiated by employees without the approval of their employer or labor union. There are various terms used to describe these types of strikes in different countries. In the United Kingdom, they are sometimes called lightning strikes while in the United States, they can be referred to as sit-down strikes, quickie strikes, or flash strikes. In Canada, they may be called wildcat, spontaneous or instant strikes. Regardless of the term used, out-law strikes can be controversial and disruptive, potentially leading to job loss and legal consequences for the participants.