Laws on crossbows
While in some countries crossbows are not subject to any specific regulation, in most there are laws, which differ widely. Each jurisdiction has its own definition of a crossbow, and in some cases pistol-sized crossbows are treated differently. There may be minimum ages for possession, and sales of both crossbows and bolts may be restricted. Specific rules around hunting use are also common.
Some jurisdictions require permits and background checks similar to those required for firearms.
Pistol crossbows are strictly controlled in all Australian states due to their concealable nature. Crossbows can be bought and owned by adults over 18 years of age, while in most states crossbows can only be owned with a special licence, for instance for members of an official sporting club. Control on transport of crossbows between states has increased to prevent unauthorised use of imported crossbows.
Recent changes to laws in Western Australia to prohibit crossbow ownership require applications to legally possess a crossbow by July 2, 2011 before they became illegal to possess and sporting usage is only legal for people currently participating in the sport at the date of the laws introduction and does not apply to or allow for new participants thereafter. 
In Bulgaria crossbows are not regulated, but their use for fishing and hunting is explicitly prohibited.
In Canada, it is legal to own a crossbow and has a similar designation as an airgun. Weapons of a projectile velocity under 500 FPS may be owned by any person 18 years of age or older. No licence is required to purchase a crossbow. Though older PAL cards say that one is allowed to acquire one, the laws designating them as firearms were struck down before they could be implemented. Crossbows designed to be fired with one hand and crossbows measuring less than 500 mm in length are prohibited.
Hunting in Canada is regulated at the provincial level, therefore the legality of crossbow hunting vary from province to province.
Crossbows and other mechanical weapons with drawing force under 150N are not regulated. Mechanical weapons above this limit are class D weapons, which means they can be used or owned by person at least 18 years (no license is required), must not be worn visibly, can be used at private places (where is no danger to health or property) and at licensed shooting ranges and at visibly marked places over-sighted by a designated person.
In Denmark, the creation or import of crossbows without a license is prohibited by Danish law on weapons (Våbenloven - Bekendtgørelse af lov om våben og eksplosivstoffer), and crossbows are not recognized as legal weapons for hunting.
In German law on weapons, crossbows and firearms are equated in their legal status as weapons (WaffG Anlage 1 1.2.2), but in contrast to guns, acquisition, possession, trade or production of crossbows requires no license (WaffG Anlage 2). Because of their definition as weapons, but without further restrictions, any crossbows can be used by minors under custody of competent adults. Fishing and hunting with crossbows is prohibited. As a specialty to be noted is that, crossbows do not shoot as per legal definition in Germany, since they don't use expanding gases or similar mechanisms to propel a projectile.
In the Netherlands crossbows are regulated by the "wet weapons en munitie" (law on weapons and ammunition). Crossbows and crossbow bolts are placed in category 4, along with bows, swords, spears, etc. It is legal to possess weapons from this category providing that the individual is over 18. It is not allowed to carry those weapons in public. When transporting, the weapon should be packaged in a way that one has to perform at least 3 actions before the weapon is ready for use (this does not include the steps required to actually load and fire the weapon). Only on special occasions such as re-enactment events this is not strictly enforced. Crossbows should be used only for collecting, re-enactment or sportive purposes. Hunting with crossbows (or bows) is strictly prohibited in the Netherlands under animal cruelty laws.
In Poland, crossbows are considered equivalent to firearms, and possession requires a license (Ustawa o broni i amunicji z 2003 roku). Hunting with crossbows is technically legal, however due to may-issue policy, crossbow licenses are usually issued for collecting purposes only.
In Sweden, crossbows are considered equivalent to firearms, and possession requires a license. Hunting with crossbows is not allowed. Swedish law dictates that any weapon that stores its energy, i.e., weapons with a firing mechanism, that produces more than 10 joules at the muzzle are illegal without licence. Thus very weak crossbows are sold in toy stores as well as low powered air rifles (not sold to minors). Sale or possession of normal bows of any strength are regulated in the same way as the previously mentioned weak crossbows and air rifles.
No licence or registration is required to own a crossbow in the United Kingdom. Under the Crossbows Act 1987, crossbows cannot be bought or sold in England, Wales or Scotland by or to those under 18. Possession is also prohibited by those under 18 years old except under adult supervision. The act states that crossbows may be used by persons under 18 years of age only when supervised by a person aged 21 years old or over. Similar prohibitions for Northern Ireland are made in the Crossbows (Northern Ireland) Order 1988. Section 5 of the Wildlife and Countryside Act 1981 prevents their use for hunting birds. In Scotland, section 50 of the Civic Government (Scotland) Act 1982  makes it illegal to be drunk in a public place in possession of a crossbow.
Section 44 of the Violent Crime Reduction Act 2006 raised the age limit from 17 to 18 in England and Wales, with effect from 1 October 2007. The Scottish Parliament made similar changes in section 62 of the Custodial Sentences and Weapons (Scotland) Act 2007, also with effect from 1 October 2007.
It is legal to own a crossbow. Rules regarding hunting with crossbow vary by state. (Laws By State)
Any licensed hunter who has obtained a free crossbow stamp can hunt with a crossbow during any season in which a firearm is allowed, for both big and small game, except hunters in the Upper Peninsula may not use a crossbow or a modified bow during the Dec. 1 - Jan. 1 late archery deer season and Dec. 7-16 muzzleloader deer season, unless the hunter is disabled and has a crossbow permit or special permit to take game with a modified bow. Any licensed hunter may use a crossbow throughout the archery deer season in the Lower Peninsula (Oct. 1 - Nov. 14 and Dec. 1 - Jan. 1) and during the early archery deer season in the Upper Peninsula (Oct. 1 - Nov. 14). Crossbow use is not allowed in the Red Oak Unit during the archery-only bear season (Oct. 5-11) except for certified hunters with a disability. The DNR may issue a crossbow permit or a special permit to take game with a modified bow to a person with a valid hunting license to take a deer during an open deer season, if the person is certified as having permanent or temporary disability, as defined in Wildlife Conservation Order 5.95, which renders a person unable to use conventional archery equipment. Hunters may use a modified bow where crossbows are legal. A modified bow is a bow, other than a crossbow, that has been physically altered so that it may be held, aimed and shot with one arm. When hunting deer, bear, elk and turkey, crossbow hunters must use only arrows, bolts and quarrels with a broadhead hunting type of point not less than 7/8 of an inch wide with a minimum of 14 inches in length. See Hunter Orange Clothing Requirements. This was taken from https://www.michigan.gov/dnr/0,4570,7-153-10366_37141_37706-31578--,00.html
Hunting with crossbow is legal to hunt game as of August 2014.
- Ausbow Industries - Australian crossbow manufacturer and agent for Excalibur crossbow
- Office of Public Sector Information - Crossbows Act 1987
- Section 50 of the Civic Government (Scotland) Act 1982
- The Crown prosecution Service - Offensive weapons retrieved 29 January 2008
- Section 62 of the Custodial Sentences and Weapons (Scotland) Act 2007