by Paul Scharre
Legally binding?
Type of Regulation
Successful?
Motivation
poisoned or barbed arrows
Dates vary - 1500 to 200 BC
Laws of Manu; Dharmaśāstras; Mahābhārata
legally binding
banned use
success unknown
unnecessary suffering
concealed weapons
Dates vary - 1500 to 200 BC
Laws of Manu
legally binding
banned use
success unknown
perfidy
fire-tipped weapons
Dates vary - 1500 to 200 BC
Laws of Manu
legally binding
banned use
success unknown
unnecessary suffering
crossbow
1097; 1139
1097 Lateran Synod; 1139 Second Lateran Council
legally binding
banned use
failed
political control
firearms
1607–1867
Tokugawa Shogunate Japan
legally binding
effectively prohibited production
successful (lasted ~250 years)
political control
firearms
1523–1543
King Henry VIII
legally binding
limited ownership among civilian population
short-lived
political control
TURN OF THE CENTURY
Era
Weapon
Year
Regulation or Treaty
Legally binding?
Type of Regulation
Successful?
Motivation
explosive or inflammable projectiles below 400 grams
1868
1868 St. Petersburg Declaration
legally binding
banned use
superseded by technology, but adhered to in spirit
unnecessary suffering
expanding bullets
1899
1899 Hague Declaration
legally binding
banned use
successful in limiting battlefield use, although lawful in civilian applications
unnecessary suffering
asphyxiating gases (from projectiles)
1899
1899 Hague Declaration
legally binding
banned use
failed - used in WW I
unnecessary suffering
poison
1899; 1907
1899 and 1907 Hague Declarations
legally binding
banned use
successful
unnecessary suffering
weapons that cause superfluous injury
1899; 1907
1899 and 1907 Hague Declarations
legally binding
banned use
mixed, but generally successful
unnecessary suffering
balloon-delivered projectiles or explosives
1899; 1907
1899 and 1907 Hague Declarations
legally binding
banned use
short-lived
civilian casualties
aerial bombardment against undefended cities
1907
1907 Hague Declaration
legally binding
banned use
failed
civilian casualties
WORLD WAR I TO WORLD WAR II
Era
Weapon
Year
Regulation or Treaty
Legally binding?
Type of Regulation
Successful?
Motivation
sawback bayonets
World War I
tacit cooperation on the battlefield
no explicit agreement
norm against possession
successful
unnecessary suffering
chemical and bacteriological weapons
1925
1925 Geneva Gas and Bacteriological Protocol
legally binding
banned use
largely successful in restraining battlefield use in WWII
unnecessary suffering
submarines
1899; 1921–1922
1899 Hague convention; 1921–1922 Washington Naval Conference
never ratified
attempted bans - never ratified
failed - treaty never ratified
civilian casualties
submarines
1907; 1930; 1936
1907 Hague Declaration; 1930 London Naval Treaty; 1936 London Protocol
legally binding
regulated use
failed - compliance collapsed in war
civilian casualties
size of navies
1922; 1930; 1936
1922 Washington Naval Treaty; 1930 London Naval Treaty; 1936 Second London Naval Treaty
legally binding
limited quantities and size of ships
short-lived
limit arms races
COLD WAR
Era
Weapon
Year
Regulation or Treaty
Legally binding?
Type of Regulation
Successful?
Motivation
nuclear tests
1963; 1967; 1985; 1995; 1996
Limited Test Ban Treaty; Treaty of Tlatelolco; Treaty of Rarotonga; Treaty of Bangkok; Treaty of Pelindaba; Comprehensive Nuclear Test Ban Treaty
legally binding
restricted testing
generally successful, with some exceptions
effects on civilians; limit arms races
weapons in Antarctica
1959
Antarctic Treaty
legally binding
banned deployment
successful
limit arms races
weapons of mass destruction in space
1967
Outer Space Treaty
legally binding
banned deployment
successful
strategic stability
weapons on the moon
1967
Outer Space Treaty
legally binding
banned deployment
successful
limit arms races
nuclear-free zones
1967; 1985; 1995; 1996
Treaty of Tlatelolco; Treaty of Rarotonga; Treaty of Bangkok; Treaty of Pelindaba
legally binding
banned developing, manufacturing, possessing, or stationing
successful
limit arms races
nuclear weapons
1970
Nuclear Non-Proliferation Treaty
legally binding
banned proliferation
generally successful, with some exceptions
strategic stability
nuclear weapons on the seabed
1971
Seabed Treaty
legally binding
banned deployment
successful
strategic stability
ballistic missile defenses
1972
Anti-ballistic Missile Treaty
legally binding
limited deployment
successful during Cold War; collapsed in multipolar world
strategic stability
biological weapons
1972
Biological Weapons Convention
legally binding
banned development, production, stockpiling, and use
generally successful, with some exceptions
unnecessary suffering; civilian casualties; prevent arms race
using the environment as a weapon
1976
Environmental Mo
dification Convention
legally binding
banned use
successful
civilian casualties; prevent arms race
antisatellite weapons
1970s & 1980s
tacit cooperation between U.S. and U.S.S.R.
no explicit agreement
norm against deployment
successful, but currently threatened in multipolar world
strategic stability
neutron bombs
1970s
tacit cooperation between U.S. and U.S.S.R.
no explicit agreement
norm against deployment
successful
strategic stability
non-x-ray-detectable fragments
1980
Convention on Certain Conventional Weapons (CCW) Protocol I
legally binding
banned use
successful
unnecessary suffering
land mines
1980
CCW Protocol II
legally binding
regulated use
unsuccessful
civilian casualties
incendiary weapons
1980
CCW Protocol III
legally binding
regulated use
mixed success
civilian casualties
chemical and biological weapons
1985
Australia Group
not legally binding
banned proliferation
mixed success
unnecessary suffering; civilian casualties
ballistic and cruise missiles
1987; 2002
Missile Technology Control Regime; Hague Code of Conduct
not legally binding
limited proliferation
has had some success
strategic stability
intermediate-range missiles
1987
Intermediate-Range Nuclear Forces (INF) Treaty
legally binding
banned possession
successful, but currently threatened in multipolar world
strategic stability
nuclear weapons and launcher quantities
1972; 1979; 1991; 2002; 2011
SALT I; SALT II; START; SORT; New START
legally binding
limited quantities
successful
limit arms races
POST–OLD WAR
Era
Weapon
Year
Regulation or Treaty
Legally binding?
Type of Regulation
Successful?
Motivation
conventional air and ground forces
1991
Conventional Forces in Europe
legally binding
limited quantities
collapsed in multipolar world
limit arms races
chemical weapons
1993
Chemical Weapons Convention
legally binding
banned development, production, stockpiling, and use
generally successful, with some exceptions
unnecessary suffering; civilian casualties
blinding lasers
1995
CCW Protocol IV
legally binding
banned use
successful
unnecessary suffering
conventional weapons
1996
Wassenaar Arrangement
not legally binding
limited proliferation
has had some success
political control
land mines
1997
Mine Ban Treaty (Ottawa Treaty)
legally binding
banned development, production, stockpiling, and use
generally successful, with some exceptions
civilian casualties
cluster munitions
2008
Convention on Cluster Munitions
legally binding
banned development, production, stockpiling, and use
generally successful, with some exceptions
civilian casualties
The result of this dynamic is that many ineffective weapons have been banned. But it is overly simplistic to say that if a weapon has value, then a ban is doomed to fail. If the only factor that mattered was the battlefield utility of a weapon, then militaries would almost certainly use poison gas. It has value in disrupting enemy operations and terrorizing enemy troops. Expanding bullets and blinding lasers—both of which are banned by treaties—also have some military utility. In these cases, though, the perceived value is low enough that states have generally not considered them important enough to break these prohibitions.
The number of countries that need to participate for a ban to succeed is also a critical factor. Arms control was easier during the Cold War when there were only two great powers. It was far more difficult in the early twentieth century, when all powers needed to agree. A single defector could cause an arms control agreement to unravel. Since the end of the Cold War, this dynamic has begun to reemerge.
Interestingly, the legal status of a treaty seems to have little to no bearing on its success. Legally-binding treaties have been routinely violated and restraint has existed in some cases without any formal agreements. International agreements, legally binding or not, primarily serve as a focal point for coordination. What actually deters countries from violating bans is not a treaty, since by default there are no legal consequences if one wins the war, but rather reciprocity. Countries show restraint when they fear that another country might retaliate in kind. When fighting nations who do not have the ability to retaliate, they have shown less restraint. For example, during World War II Japan used chemical weapons in small amounts against China, who did not have them, and Germany killed millions of people in gas chambers during the Holocaust. Neither country used poison gas against adversaries who could retaliate in kind.
For mutual restraint to occur, there must be a clear focal point for coordination. In his books Strategy of Conflict and Arms and Influence, Thomas Schelling explained that “the most powerful limitations, the most appealing ones, are those that have a conspicuousness and simplicity, that are qualitative and not a matter of degree, that provide recognizable boundaries.” Schelling observed:
“Some gas” raises complicated questions of how much where, under what circumstances: “no gas” is simple and unambiguous. Gas only on military personnel; gas used only by defending forces; gas only when carried by vehicle or projectile; no gas without warning—a variety of limits is conceivable; some may make sense, and many might have been more impartial to the outcome of the war. But there is a simplicity to “no gas” that makes it almost uniquely a focus of agreement when each side can only conjecture at what rules the other side would propose and when failure to coordinate on the first try may spoil the chances for acquiescence in any limits at all.
This simplicity undoubtedly played a role in making it possible for European nations to refrain from using poison gas against each other in World War II, in spite of a total war that devastated the continent.
Germany and the United Kingdom also attempted to mutually avoid bombing attacks on civilian targets. These failed, but not necessarily because aerial bombing was more effective than gas or less horrible. Aerial bombing of cities was largely ineffective and universally reviled. The main purpose of Britain and Germany launching these attacks seemed to be relation for the other having done so.
The chief difference between aerial bombardment and gas, and what made restraint with aerial bombardment so difficult, is that restraint against civilian targets lacked the clarity and simplicity of the “no gas” rule. Bombers were already used in other capacities outside of attacks on cities. First they were used against ships, then land-based military targets (which inevitably had civilian
casualties), then eventually cities. Each of these steps was gradual. Escalation from one step to another could even happen by accident. In fact, the final step toward full-scale aerial bombardment seems to have occurred because of an accident. Early in the war, Hitler gave explicit instructions to the Luftwaffe to avoid attacks on cities and stick to military targets, because he was worried about British reprisals. On August 24, 1940, however, several German bombers strayed in the dark and bombed central London by mistake. The British retaliated by hitting Berlin. Hitler was incensed. In a public speech, he declared, “If they declare that they will attack our cities on a large scale—we will eradicate their cities.” Germany launched the London Blitz, and all attempts at restraint were gone. Gas was different. Moving from “no gas” to suddenly using it crossed a clear threshold. It was an unambiguous decision to escalate. Had gas been used on the battlefield against military targets, it likely would have expanded to attacks on cities as well.
Treaties that completely ban a weapon tend to be more successful than complicated rules governing a weapon’s use. Other attempts to regulate how weapons are used on the battlefield in order to avoid civilian casualties—such as restrictions on submarine warfare, incendiary weapons, and the CCW land mine protocol—have had a similarly poor track record of success. Complete bans on weapons—such as those on exploding bullets, expanding bullets, chemical weapons, biological weapons, environmental-modification weapons, and blinding lasers—have fared better.
Two interesting exceptions that seem to prove this rule are the bans on land mines and cluster munitions. Both treaties articulate a simple and straightforward prohibition in their text. States who sign the treaties pledge “never under any circumstances to use” land mines and cluster munitions. That’s about as straightforward as it gets, a clear and simple prohibition. The complicating details are buried in the definitions. In both cases, the definitions are written in such a way to carve out loopholes for certain existing weapons. The definition of “antipersonnel land mine” permits anti-vehicle mines, including those that have anti-handling devices (which are lethal to people). The cluster munitions convention has an even more complicated definition that covers the number and weight of submunitions. The effect is to permit many weapon systems that, to an ordinary person, would appear to be cluster munitions. This is no accident. The definition was crafted in such a way during negotiations to permit some countries to retain their existing inventories of now-not-quite-cluster-munitions. During signing, Australia made clear that the treaty would not cover its SMArt 155 artillery shells, which dispense two antitank submunitions. By burying these complicated rules in the definitions, though, the ban has the appearance of clarity, making it a stronger ban from a normative perspective. It’s easier to stigmatize a weapon if it is perceived as illegitimate in all circumstances. “No cluster munitions” is simpler and easier to justify than “these cluster munitions, but not those,” even though in practice that’s what the ban does.
