LINE is a close-quarters combat system, derived from various martial arts, utilized by the United States Marine Corps between 1989 and 1998, and then from 1998 to 2007 by US Army Special Forces.

[citation needed] Officially, the name stands for "Linear Involuntary Neural-override Engagement"; this is, however, a backronym coined during the project's inception.

Techniques like classic judo "hip throws", for instance, were excluded because of the possibility of entanglement on a practitioner's war-belt.

The requirement and demands that the system be drilled, repeated, and constantly revisited led to some criticism since the primary users – military, including special operations, personnel – often had enormous demands upon their time, and as a consequence often lacked the ability to maintain high degrees of proficiency in the techniques.

LINE was adopted by the Marine Corps in 1989 at a Course Content Review Board (CRB) at Quantico, Virginia.