North America 
In the mid to late 1970s, the Canadian Radio-television and Telecommunications Commission (CRTC) implemented a rule that a cable system must carry a terrestrial TV channel at no cost to the terrestrial broadcaster so long as the transmitter emitted at least 5w EIRP. This CRTC rule may have changed over the years, but in principle a 1 kW EIRP terrestrial TV station must be carried. The status of terrestrial digital only channels with respect to the must-carry requirement is untested as, unlike the US, very little ATSC is on-air in Canada as of 2008[update] and the few channels active are merely HDTV versions of existing analog programming in major centres such as Toronto and Vancouver with no additional digital subchannels offered.
CITY-TV of Toronto (according to its own website and annual reports) owes its financial success as an independent TV station to this CRTC must-carry rule. It is assumed that this must-carry rule was aimed at small TV stations in Ontario and Quebec, many of which are not carried by satellite television providers.
For many years, the Canadian must-carry rules created very little friction between terrestrial broadcasters and cable systems, as cable systems are allowed to more aggressively implement other digital telecommunications services (like cable internet services and IP telephony) with less overall regulation than their US counterparts. However, in 2008, Canada's two largest commercial television networks, CTV and Global, began to demand that the CRTC permit them to charge a fee for cable carriage, even alleging that some smaller market stations would be forced to close if this was not allowed.
United States 
In the United States, the Federal Communications Commission (FCC) regulates this area of business and public policy. These rules were upheld in a 5-4 decision by the Supreme Court of the United States in 1997 in the case Turner Broadcasting v. FCC (95-992). The United States was the first country to implement a must-carry scheme.
Although cable TV service providers routinely carried local affiliates of the major broadcast networks, independent stations and affiliates of minor networks were sometimes not carried, on the premise it would allow cable providers to instead carry non-local programming which they felt would attract more customers to their service.
Many cable operators were also equity owners in these cable channels, especially TCI, then the nation's largest multiple system operator (MSO), and had moved to replace local channels with equity-owned programming (at the time, TCI held a large stake in Discovery Communications). This pressure was especially strong on cable systems with limited bandwidth for channels.
The smaller local broadcasters argued that by hampering their access to this increasing segment of the local television audience, this posed a threat to the viability of free-to-view broadcast television, which they argued was a worthy public good.
Local broadcast stations also argued cable systems were attempting to serve as a "gatekeeper" in competing unfairly for advertising revenue. Some affiliates of major networks also feared that non-local affiliates might negotiate to provide television programming to local cable services to expand their advertising market, taking away this audience from local stations, with similar negative impact on free broadcast television.
Although cable providers argued that such regulation would impose an undue burden on their flexibility in selecting which services would be most appealing to their customers, the current "must-carry" rules were enacted by the U.S. Congress in 1992 (via the Cable Television Protection and Competition Act), and the U.S. Supreme Court upheld the rules in rejecting the arguments of the cable industry and programmers in the majority decision authored by Justice Anthony Kennedy. That decision also held that MSOs were functioning as a vertically integrated monopoly.
A side effect of the must-carry rules is that broadcast networks cannot charge the cable TV companies license fees for the program content retransmitted on the cable network, except potentially as a part of retransmission consent agreements in lieu of must-carry.
There are a few exceptions, most notably:
- Must-carry may only be applied if the television station wants to be carried under this provision. This only applies to non-commercial educational (NCE) stations. Station operators are allowed to demand payment from cable operators, or negotiate private agreements for carriage, or threaten revocation against the cable operator (see Sinclair, Time Warner Cable). Must-carry is a privilege given to television stations, not a cable company. A cable company cannot use must-carry to demand the right to carry an OTA station against the station's wishes.
- A station does not have distribution under must-carry legislation until a certain number of days after it provides usable signal to the headend for the cable or satellite provider; the station must pay the expense of leased lines to reach providers such as Colorado-based Dish Network or California-based DirecTV.
- Foreign signals, such as Windsor stations CBET-DT CICO or McAllen's Fox affiliate (XHRIO-TV), are not required to be carried, but are often carried on border-area cable systems close to the foreign stations.
- Most low-power broadcast stations are not required to be carried, although often in these cases they are bundled to be carried as part of a retransmission consent agreement with a full-power sister station.
Digital must-carry 
Digital must-carry — also incorrectly called "dual must-carry" — is the requirement that cable companies carry either the analog (in an analog & digital cable system) or digital (in a digital-only TV system like AT&T U-verse or Verizon FiOS) signal. They must still meet the every-subscriber/TV receiver laws, i.e. "Pursuant to Section 614(b)(7) and 615(h), the operator of a cable system is required to ensure that signals carried in fulfillment of the must-carry requirements are provided to EVERY subscriber of the system,” of local stations. This has been opposed by numerous cable networks, who might be bumped off of digital cable were this to happen, and promoted by TV stations and the National Association of Broadcasters, whom it would benefit by passing their HDTV or multichannel DTV signals through to their cable viewers. In June, 2006 the FCC was poised to pass new digital must-carry rules, but the item was pulled before a vote actually took place, apparently due to insufficient support for the chairman's position.
In September, 2007, the Commission approved a regulation that requires cable systems to carry the analog signals if the cable system uses both types of transmission. They left the decision to also retransmit the digital signal up to the cable provider. Digital only operators are not required to provide an analog signal for their customers (AT&T U-verse, Verizon FiOS). Small cable operators were allowed to request a waiver. The regulation will end three years after the digital TV transition date, and applies only to stations not opting for retransmission consent.
Cable operators (analog & digital) that transmit more than 12 channels need only provide a maximum 1/3 of their total channel size to this must-carry requirement. Thus with about 150 channels available to a 1 GHz operator, they are only required to support up to 50 analog channels (42 for 850 MHz, 36 for 750 MHz). Cable provider who decide to scale back their analog selection merely need provide written notification on their bill (or equivalent) for 30 days prior to their change. Customers already using digital cable set top boxes will usually be unaffected (if anything after the change they may get a huge number of additional channels because each analog channel can be replaced by 2-51 digital channels). The requirement only applies to must-carry stations; most metro providers carry many more analog stations by choice, not law.
Other networks 
A variation of "must-carry" also applies to DBS services like DirecTV and Dish, as first mandated by the Satellite Home Viewer Act of 1988. They are not required to carry local stations in every metro area in which they provide service, but must carry all of an area's local stations if they carry any at all. Sometimes, these will be placed on spot beams: narrowly-directed satellite signals targeted to an area of no more than a few hundred miles diameter, in order to allow the transponder frequencies to be re-used in other markets. In some cases, stations of lower perceived importance are placed on "side satellites" which require a second antenna. This practice has raised some controversy within the industry, leading to the requirement that the satellite provider offer to install any extra dish antenna hardware for free and place a notice to this effect in place of any missing channels.
Retransmission consent 
If a broadcaster elects retransmission consent, there is no obligation for the cable system to carry the signal. This option allows broadcasters who own popular stations, such as CBS, NBC and ABC or Fox to request cash or other compensation from cable or satellite providers for signals. These networks have usually attempted to gain further distribution of cable services and/or co-owned low power television stations in which they also hold an equity position rather than direct cash compensation, which cable systems have almost universally balked at paying. In some cases, these channels have been temporarily removed from distribution by systems who felt broadcasters were asking too steep a price for their signal. Examples include the removal of all CBS-owned local stations plus MTV, VH1 and Nickelodeon from DISH Network for two days in 2004, the removal of ABC-owned stations from Time Warner Cable for a little under a day in 2000, and the removal of all Hearst Television local stations from Time Warner for more than a week in 2012.
In the U.S. retransmission consent has often been chosen over must-carry by the major commercial television networks. Under the present rules, a new agreement is negotiated every three years, and stations must choose must-carry or retransmission consent for each cable system they wish their signal to be carried on. Non-commercial stations (such as local PBS stations) may not seek retransmission consent and may only invoke must-carry status.
See also 
Republic of Ireland 
The same rules apply to digital MMDS. Analogue MMDS companies are required to carry only TV3 due to serious bandwidth limitations.
Czech republic 
In the Czech republic all TV stations with terrestrial licence (analog or digital) have to be in the lowest (cheapest) offer of all cable, IPTV and satellite companies.
Must-carry regulations is applied to:
- All channels of Czech Television - ČT1, ČT2, ČT24 and ČT4 (sport)
- All channels of TV Prima - Prima, Prima Cool and R1 TV
- Two of three channels of TV Nova - Nova and Nova Cinema
- New digital TV stations - TV Barrandov and Z1
- Future television stations TV7 (regional news) and RTA (regional TV)
- Carriage of TV Pohoda and Febio TV was also mandated by must-carry regulations; however, as investments for these channels were pulled, these channels never commenced broadcasting.
In India, government has applied must-carry rule for public broadcaster channels from Doordarshan by Cable, DTH and IPTV network. Cable TV operators must offer National (DD1), DD News, Loksabha, Rajyasabha and Regional channels to all subscribers. In addition, DD Bharti and DD Urdu must also be carried in their appropriate tiers.