The title is a reference to the 1968 Nuclear Non-Proliferation Treaty. The meaning and relevance is as defined on the Australian video cassette sleeve: "The Fourth Protocol is a secret agreement between the Soviet powers and the Western allies forbidding the importation of component parts of a nuclear bomb into the territory of any nation." As such, one of the movie's taglines declares, "If the Fourth Protocol is ever breached, there would be no warning, just a nuclear explosion from a bedsitter."
The Fourth Protocol is a fictional secret protocol of the 1968 Nuclear Non-Proliferation Treaty, containing an agreement between nuclear powers that nuclear weapons will only be delivered to their target by conventional means, e.g. dropped from aircraft or on missiles. In the world of the film, it effectively prevents them being left in luggage lockers or delivered by postal companies or other clandestine means.
Sir Michael Caine once said of this film in his autobiography "What's It All About?" (1992): "We wound up with a wordy action movie which, although it was quite a good picture, and did fair business, never had the speed and pace of the best American action movies. So for long sequences in the film, we not only had a talking picture, but a lot of talk, and even worse, most of it unintelligible. I went there as the star and Associate Producer, and one might have thought this would give me sufficient authority to put my own strongly-held opinions into practice, but no chance. Even I, in my exalted position, wound up making a talking picture, when it should have been a moving one."
Sir Michael Caine and author Frederick Forsyth had been friends for around a decade prior to this picture. In the three earlier filmed adaptations of Forsyth novels, Caine was never selected to be in them. So the two decided raise the financing themselves, so as to make sure they could work on a movie together. The two are billed as Executive Producers on this movie.
The movie featured Matryoshka dolls, a.k.a. Russian nesting dolls, or Russian nested dolls. These had become popularized, and well-known from appearing in the opening title sequence of the earlier television production of John Le Carré's Tinker Tailor Soldier Spy (1979).
The spy film that Pierce Brosnan made before becoming James Bond in GoldenEye (1995). Ironically, it was the same year that The Living Daylights (1987) was released. That was the Bond film, for which Brosnan was originally cast, but in the end, could not do, due to his contract being picked up for further episodes of Remington Steele (1982).
A video game of "The Fourth Protocol" was developed and released in 1985. As such, the video game has the distinction of being made before, and not at the same time, or after, the movie. The computer game was made for the Commodore 64 and ZX Spectrum home computer platforms.
The film starred Sir Michael Caine and featured Michael Gough. Both have played Bruce Wayner's butler Alfred Pennyworth in the Batman and Dark Knight movies. This was the only film in which they both appeared.
The film's opening prologue states: "1963 - top British Agent Kim Philby defected to Moscow. 1968 - America, Britain, Russia signed an agreement to halt the spread of nuclear weapons. This treaty continued four secret protocols. Today - only one remains."