Question: By what act is the counter-espionage branch Michael John Bettaney worked for bound?

Context paragraphs:
Michael J. Pollard: Michael John Pollard (born Michael John Pollack Jr.; May 30, 1939) is an American actor best known for playing the character C. W. Moss in the 1967 crime film "Bonnie and Clyde".

Michael Wilk: Michael John Wilk (born "circa" 1955 in Chicopee, Massachusetts) is an American keyboardist, songwriter, and record producer best known for his contributions to John Kay and Steppenwolf.  He has also worked with Boz Scaggs, Mick Fleetwood, Christine McVie, Billy Burnette, Phil Seymour, Danny Hutton, the Pointer Sisters, Tom Scott, and the actor Scott Baio.  Working with Steve Cropper of Booker T. & the M.G.'s and the Blues Brothers, Wilk performed and recorded the music for the movie "Satisfaction".  Wilk also worked on the "Pretty In Pink" soundtrack and has worked on television commercials.  He currently works in his recording studio in Portland, Oregon.  He also currently works with the University of Alabama Million Dollar Band.

Michael Atkinson: Michael John Atkinson (born 17 June 1958), an Australian politician in the South Australian Branch of the Australian Labor Party, is the 34th Speaker of the South Australian House of Assembly for the Jay Weatherill government, serving since 5 February 2013.  First elected to the House at the 1989 election, Atkinson is Father of the House.

Mick McLaren: Air Marshal Michael John "Mick" McLaren CLM (18 November 1930 – 29 July 2016) was a senior commander in the Rhodesian Air Force.  McLaren was in command of the Rhodesian Air Force from 1973 to 1977.  Thereafter he was Deputy Commander of Combined Operations until 1980 when he retired from military service and worked in the oil industry.  He died from cancer on 29 July 2016.

MI5: The Security Service, also MI5 (Military Intelligence, Section 5), is the United Kingdom's domestic counter-intelligence and security agency and is part of its intelligence machinery alongside the Secret Intelligence Service (MI6), Government Communications Headquarters (GCHQ) and Defence Intelligence (DI).  MI5 is directed by the Joint Intelligence Committee (JIC), and the service is bound by the Security Service Act 1989.  The service is directed to protect British parliamentary democracy and economic interests, and counter terrorism and espionage within the UK.

MI5(g): The MI5(g), or the MI5 G section, was a branch of MI5 that was formed during World War I to address the wartime espionage operation by the Indian revolutionary movement in Europe.  The department arose by renaming the MO5(g), which was renamed MI5(g) in 1916.  The MI5 itself, working under Vernon Kell, had a number of India experts at the beginning of the war.  In September 1916, a special section, the MI5(d), section was formed to operate counter-espionage networks throughout the British Empire.  Another subsection, the MI5(b), was formed in January 1917 to deal specifically with Indians and "other oriental races".  The MI5(g) had 27 officers in its staff, eight of whom had served in India before the war.  Among them were ex-Indian civil servants including Robert Nathan and H. L. Stephenson.  The main emphasis of this counter-espionage network was to prevent the subversion of Indian troops in the European theatre.  The organisation, especially under Nathan, worked closely with the Special Branch of the Scotland Yard in Britain and with the Indian Political Intelligence Office headed by John Wallinger, which operated a network of spies in neutral Switzerland which a number of the Indian revolutionaries and members of the Berlin Committee used as a base.

From the Towers of the Moon: From the Towers of the Moon is an opera in one act by Robert Moran, with a libretto by Michael John LaChiusa.  It is based on the classic Japanese tale "Princess Kaguya", or "The Tale of the Bamboo Cutter", which tells of a princess from the moon who comes to Earth.  Moran knew the story as "The Tale of the Shining Princess" and had seen a film adaptation of the legend made by Kon Ichikawa in 1987.

See What I Wanna See: See What I Wanna See is a musical by Michael John LaChiusa based on three short stories by Ryūnosuke Akutagawa: "Kesa and Morito", "In a Grove" (the inspiration also for Akira Kurosawa's "Rashomon") and "".  The story is told in two parts with two prologues.  Each prologue involves the medieval lovers/killers Kesa and Morito.  The first act follows a murder in Central Park in 1951 from the various perspectives of several different characters.  Act two centers on a priest, wavering in his faith, who creates a hoax about a miracle.

Michael J. Wendl: Michael John Wendl (born June 6, 1934) is an engineer who worked at the McDonnell-Douglas Corporation, mainly in the area of aerospace control.  He is noted primarily as one of the early developers of terrain following technology and a proponent of incorporating energy management theory into the design of fighter aircraft.  He won the Wright Brothers Medal in 1974 with Ralph Pruitt, Gordon G. Grose, and J. L. Porter for a paper discussing future aircraft designs that integrate fly-by-wire controls with engine inlets/nozzles and advanced pilot displays.

Michael Bettaney: Michael John Bettaney (born 13 February 1950) was an intelligence officer working in the counter-espionage branch of MI5 who was convicted at the Old Bailey in 1984 of offences under section 1 of the Official Secrets Act 1911 after passing sensitive documents to the Soviet Embassy in London and attempting to act as an agent-in-place for the Soviet Union.

Supporting paragraphs: Michael Bettaney MI5
Answer: Security Service Act 1989