Lou Laat Do (abbr. LLD/C-JKD, LLD C-JKD, or simply LLD; from Cantonese lou laat: efficient but unscrupulous, and do[u]: way) denotes a particular modern military hand-to-hand combat system dealing with ground fighting, unarmed stand-up fighting, and short-range weapons fighting, using exclusively no-block and no-gi techniques with an emphasis on empty hand techniques and trapping range termination. Its development was initiated in (West) Berlin, Germany, in September 1979.
The term Lou Laat Do has been created retrospectively because it was only referred to as part of close-quarters combat training at that time when there was no internal need to verbally distinguish this system from other combat systems.

Lou Laat Do is an eclectic/hybrid combatives system which rejects any block-and-counter concepts in favor of more efficient straightforward aggressive techniques. Using present-day terms, it can be described as a synthesis of basic Jeet Kune Do concepts, the full Rapid Assault Tactics fighting system, the most effective Tekken Ryu Jujutsu ground fighting techniques, selected Brazilian Jiu-jitsu/Kinamutay combinations, Eskrima basics, and selected Krav Maga techniques.
Generally, Lou Laat Do can be regarded as a variant of Contemporary Jeet Kune Do.

Unlike fighting sports, in which lethal and seriously harmful techniques are banned by restrictive rules that normally lead to the win of the physically superior, military combat systems even focus on these techniques. Of course, this also applies to Lou Laat Do which, therefore, is not a sport and does not employ any competitions. It does not even apply any rules of engagement or a use of force continuum. Furthermore, in Lou Laat Do, no detailed ranking system such as the use of belt color ranks is established. Instead, there are simply "beginners" which are still learning the techniques, "practitioners" which have completed the learning phase, and the "trained" which have already functionalized all techniques, and each well-trained individual can easily act as an instructor.
Lou Laat Do has been developed to combine the most suitable techniques of the most suitable martial arts to be able to create and maintain an effective combatant from any average person with no special skills with a minimum amount of effort and time. Its tactics and techniques are appropriate to neutralize even highly skilled and physically superior opponents in several seconds. The scenarios covered are fighting hand-to-hand, weapon-to-weapon, weapon-to-hand, hand-to-weapon, and multiple attackers, but the Lou Laat Do techniques are not well-suited for fighting against body-armored opponents which can be better dealt with by martial arts focusing on throws, joint locks, and the like, e.g. some traditional systems such as Kyushin Ryu Jujutsu.

Since the Lou Laat Do techniques' easy-to-perform moves themselves are not suitable for general physical fitness training, the first part of each training session is devoted to predominantly anaerobic fast and plyometric calisthenics, rapid repetition sets of all kinds of strikes of all limbs, and stretching exercises to develop physical attributes such as strength, speed, flexibility, and endurance.
This improves not only the execution of the Lou Laat Do combat techniques but also the performance of "primal fighting" which is a Lou Laat Do term for the way a technically completely untrained person fights by executing only congenital reflex actions and instinctive behavior. This is important for situations where one is so much overwhelmed by an attack that he temporarily loses control over his techniques flow, thus falling back to primal fighting which is technically weak and therefore requires much more advanced physical attributes.
The second part of each training session is spent with practicing the actual combat techniques. Ca. 35% of the formal (i.e. non-sparring) combat techniques training time is devoted to ground fighting techniques, and ca. 20% is devoted to trapping techniques mainly taken from Wing Chun. Much of the sparring is restricted to no or light contact, or it is done using appropriate protective equipment.