The Constitution of Canada is the supreme law in Canada ;  the country's constitution is an amalgamation of codified acts and uncodified traditions and conventions. Canada is one of the oldest constitutional democracies in the world.  The constitution outlines Canada's system of government, as well as the civil rights of all Canadian citizens and those in Canada. 
The composition of the Constitution of Canada is defined in subsection 52(2) of the Constitution Act, 1982 as consisting of the Canada Act 1982 (including the Constitution Act, 1982), all acts and orders referred to in the schedule (including the Constitution Act, 1867, formerly the British North America Act, 1867), and any amendments to these documents.  The Supreme Court of Canada has held that the list is not exhaustive and includes a number of pre-confederation acts and unwritten components as well.  See list of Canadian constitutional documents for details.
History of the constitution
The first semblance of a constitution for Canada was the Royal Proclamation of 1763.  The act renamed the northeasterly portion of the former French province of New France as Province of Quebec, roughly coextensive with the southern third of contemporary Quebec. The proclamation, which established an appointed colonial government, was the de facto constitution of Quebec until 1774, when the British parliament passed the Quebec Act, which expanded the province's boundaries to the Ohio and Mississippi Rivers, which was one of the grievances listed in the United States Declaration of Independence. Significantly, the Quebec Act also replaced the French criminal law presumption of guilty until proven innocent with the English criminal law presumption of innocent until proven guilty; but the French code or civil law system was retained for non-criminal matters. 
The Treaty of Paris of 1783 ended the American War of Independence and sent a wave of British loyalist refugees northward to Quebec and Nova Scotia.  In 1784, the two provinces were divided; Nova Scotia was split into Nova Scotia, Cape Breton Island (rejoined to Nova Scotia in 1820), Prince Edward Island, and New Brunswick, while Quebec was split into Lower Canada (southern Quebec) and Upper Canada (southern through lower northern Ontario). The winter of 1837–38 saw rebellion in both of the Canadas, with the result they were rejoined as the Province of Canada in 1841. This was reversed by the British North America Act in 1867 which established the Dominion of Canada. 
Initially, on 1 July 1867, there were four provinces in confederation as "One dominion under the name of Canada": Canada West (former Upper Canada, now Ontario), Canada East (former Lower Canada, now Quebec), Nova Scotia, and New Brunswick.  Title to the Northwest Territories was transferred by the Hudson’s Bay Company in 1870 and the province of Manitoba (the first to be established by the Parliament of Canada) was in the same year the first created out of it. British Columbia joined confederation in 1871, followed by Prince Edward Island in 1873. The Yukon Territory was created by Parliament in 1898, followed by Alberta and Saskatchewan in 1905. The Dominion of Newfoundland, Britain's oldest colony in the Americas, joined Canada as a province in 1949. Nunavut was created in 1999.
An Imperial Conference in 1926 that included the leaders of all Dominions and representatives from India (which then included Burma, Bangladesh, and Pakistan), led to the eventual enactment of the Statute of Westminster 1931. The statute, an essential transitory step from the British Empire to the Commonwealth of Nations, provided that all existing Dominions became fully sovereign of the United Kingdom and all new Dominions would be fully sovereign upon the grant of Dominion status.  Newfoundland never ratified the statute, so it was still subject to imperial authority when its entire system of government and economy collapsed in the mid-1930s. Canada did ratify the statute, but had requested an exception because the Canadian federal and provincial governments could not agree on an amending formula for the Canadian constitution. It would be another 50 years before this was achieved. In the interim, the British parliament periodically passed enabling acts with respect to amendments to Canada's constitution; this was never anything but a rubber stamp. 
The patriation of the Canadian constitution was achieved in 1982 when the British parliament, with the assent of the Canadian parliament, passed the Canada Act, 1982, which included in its schedules the Constitution Act, 1982, the United Kingdom thus formally absolving itself of any remaining responsibility for, or jurisdiction over, Canada. In a formal ceremony on Parliament Hill in Ottawa, Queen Elizabeth II proclaimed both acts as law on 17 April 1982.  Constitution Act, 1982, included the Canadian Charter of Rights and Freedoms. Prior to the charter, there were various statutes which protected an assortment of civil rights and obligations, but nothing was enshrined in the constitution until 1982. The charter has thus placed a strong focus upon individual and collective rights of the people of Canada. 
Enactment of the Charter of Rights and Freedoms has also fundamentally changed much of Canadian constitutional law.  The act also codified many previously oral constitutional conventions and made amendment of the constitution significantly more difficult. Previously, the Canadian federal constitution could be amended by solitary act of the Canadian or British parliaments, by formal or informal agreement between the federal and provincial governments, or even simply by adoption as ordinary custom of an oral convention or unwritten tradition that was perceived to be the best way to do something. Since the act, amendments must now conform to certain specified provisions in the written portion of the Canadian constitution.
Constitution Act, 1867
This was an Act of the British parliament, originally called the British North America Act 1867. It outlined Canada's system of government, which combines Britain's Westminster model of parliamentary government with division of sovereignty ( federalism). Although it is the first of 20 British North America Acts, it is still the most famous of these and is understood to be the document of Canadian Confederation. With the patriation of the Constitution in 1982, this Act was renamed Constitution Act, 1867 . In recent years, the 1867 document has mainly served as the basis on which the division of powers between the provinces and federal government have been analyzed.
Constitution Act, 1982
Endorsed by all provincial governments except that of Quebec (led by René Lévesque), this was the formal Act of Parliament that effected Canada's full political independence from the United Kingdom. Part V of this act established an amending formula for the Canadian constitution, the lack of which (due to more than 50 years of disagreement between the federal and provincial governments) was the only reason Canada's constitutional amendments still required approval by the British parliament after enactment of the Statute of Westminster in 1931.
The Act was enacted as a schedule to the Canada Act 1982, a British Act of Parliament which was introduced at the request of a joint address to the Queen by the Senate and House of Commons of Canada. As a bilingual act of parliament, the Canada Act 1982 has the distinction of being the only legislation in French that has been passed by an English or British parliament since Norman French ( Law French) ceased to be the language of government in England. In addition to enacting the Constitution Act, 1982, the Canada Act 1982 provides that no further British Acts of Parliament will apply to Canada as part of its law, finalizing Canada's legislative independence.
Canadian Charter of Rights and Freedoms
As noted above, this is Part I of the Constitution Act, 1982. The Charter is the constitutional guarantee of the civil rights and liberties of every citizen in Canada, such as freedom of expression, of religion, and of mobility. Part II addresses the rights of Aboriginal peoples in Canada.
It is written in plain language in order to ensure accessibility to the average citizen. It only applies to government and government actions with the intention to prevent government from creating laws that are unconstitutional.
Instead of the usual parliamentary procedure, that includes the monarch's formal Royal Assent for enacting legislation, amendments to the Constitution Act, 1982 must be done in accordance with Part V of the Constitution Act, 1982, which provides for five different amending formulae. Amendments can be brought forward under section 46(1) by any province or either level of the federal government. The general formula is set out in section 38(1), known as the "7/50 formula", requires: (a) assent from both the House of Commons and the Senate; (b) the approval of two-thirds of the provincial legislatures (at least seven provinces) representing at least 50% of the population (effectively, this would include at least Quebec or Ontario, as they are the most populous provinces). This formula specifically applies to amendments related to the proportionate representation in Parliament, powers, selection, and composition of the Senate, the Supreme Court and the addition of provinces or territories.
The other amendment formulae are for exceptional cases as provided by in the act. In the case of an amendment related to the Office of the Queen, the use of either official language (subject to section 43), the amending formula itself, or the composition of the Supreme Court, the amendment must be adopted by unanimous consent of all the provinces in accordance with section 41. In the case of an amendment related to provincial boundaries or the use of an official language within a province alone, the amendment must be passed by the legislatures affected by the amendment (section 43). In the case of an amendment that affects the federal government only, the amendment does not need approval of the provinces (section 44). The same applies to amendments affecting the provincial government alone (section 45).
Vandalism of the proclamation paper
In 1983, Peter Greyson, an art student, entered Ottawa's National Archives (known today as Library and Archives Canada) and poured red paint mixed with glue over a copy of the proclamation of the 1982 constitutional amendment. He said he was displeased with the federal government's decision to allow United States missile testing in Canada and had wanted to "graphically illustrate to Canadians" how wrong he believed the government to be. Greyson was charged with public mischief and sentenced to 89 days in jail, 100 hours of community work, and two years of probation.  A grapefruit-sized stain remains on the original document; restoration specialists opted to leave most of the paint intact, fearing that removal attempts would only cause further damage.