When a Islamic country implements a form of Sharia law, what exactly does that mean in terms of the actual policies being put in place?
I mean, I know exact definitions vary considerably, but what concepts do they generally share?
Sharia law is a big and complex subject. A significant number of college students in Saudi Arabia and in Iran, for example, would have it has a college major and pursue graduate studies in it as well. This post focuses on some of the better known and most distinctive features of it from the perspective of an outsider.
Needless to say, given the limitations of space and the audience, this treatment grossly oversimplifies the matter in the hope of getting across some key points that would be relatively widely shared in jurisdictions seeking to implement Sharia law. None of the points in this answer should be regarded as complete or authoritative. Instead, they are illustrative, simplified, analogized to more familiar concepts for non-Muslims, and typical to the point of being stereotypical.
In particular, as an outsider who has no personal day to day experience in an Islamic law country, there are some points upon which I am not comfortable saying that they would or would not be included in a Sharia law country or accurately describing the extent of those practices and their basis. Where I have been unsure or I am unclear, I am silent on those points.
Notable Islamic Law Principles
Some of the Islamic law concepts that would be most notable and distinctive to English speaking Christian and secular people would include the following, with links to other components of Islamic law by subject area found here.
Various forms of corporal punishment for conduct that constitutes a subset of crimes for which specific punishments are established under Islamic law, called hudud punishments, which are usually viewed as harsh by outsiders, such as amputation of a hand for theft and the death penalty for offenses including adultery, blasphemy and witchcraft, subject to various limiting doctrines like the ability of a victim's family to accept blood money in lieu of an execution. Lashing is another form of punishment called for in the case of certain offenses in Islamic law.
Women's testimony is inferior to men's in criminal proceedings and in part as a consequence of this, there are high barriers to rape prosecutions with a failed prosecution attempt likely to result in punishment for the rape victim.
Family and Family Property Law
The ability of men to marry up to four wives at any given time and to divorce summarily by formally uttering "I divorce you" three times (triple talaq). In many places where this is implemented, it would also involve legalizing the concept of "temporary marriage" which is essentially a form of legalized prostitution in practice in some places.
Islamic inheritance laws apply.
Broadly applicable economic principles
A ban on charging interest although Islamic finance concepts that involve notions like periodic purchase of what amount to tenancy in common interests in property and renting the percentage of the property that has not been purchased are available. In practice, transactions which give rise to the equivalent of compound interest are forbidden, while transactions that give rise to the economic equivalent of simple interest can be arranged.
Certain kinds of non-Muslims (basically "People of the Book") are permitted to exist in a community as second class citizens, but only if they pay an Islamic law prescribed tax (Jizya) and only if they are not converts from Islam (conversion from Islam has a hudud punishment of death).
Charitable contributions of 1/40th of one's income analogous to a tithe (Zakat) are required.
Enforcement of Islamic religious mandates in daily life
Some countries where Islamic law is mandated enforce religious mandates (particularly those that do not have hudud punishments) in daily life through a specialized institution which in Saudi Arabia is known as the "Committee for the Promotion of Virtue and the Prevention of Vice" which is a parallel policing system of second class minor religious law enforcers, who can nonetheless exert a great deal of influence on how people live their day to day lives. Some of these commands include:
The call to prayer, five times a day (Salat), will generally interrupt daily life and will be broadcast over some sort of public address system.
Required male circumcision, traditionally conducted upon early adolescent boys. The extent to which female circumcision, a.k.a. female genital mutilation, is considered Islamic law as opposed to a cultural tradition varies regionally.
Women are required to be "modest" in appearance, although this manifests itself differently in different places.
Islamic rules on clean and unclean foods (halal) would be implemented.
Alcohol (or more precisely khamr whose meaning is a subject of differences of opinion in Islamic law) is banned.
Representational art (i.e. art that realistically depicts people or things) can become a touchy subject that is prohibited unless it can overcome concerns though rather elaborate theological analysis.
Sharia law does not preclude the existence of secular laws as well. For example, a place with Sharia law can still have speed limits for motor vehicles which obviously didn't exist in the formative years of the Islamic faith. But, Sharia law will override conflicting secular law in much the same manner that the U.S. Constitution will override other statutes and treaties. See, e.g., Article Three of the Constitution of Afghanistan.
The procedural implementation of Sharia law, particularly in Sunni Islam, can be rather tricky, because Sunni Islam does not have a unified religious hierarchy the way that the Roman Catholic Church and many other established church denominations do. Organizationally, Sunni Islam is organized more like Baptist churches or independent non-denominational churches are in the United States without a body that has supreme authority over everyone in the faith. (Most forms of Shia Islam have a more hierarchical organizational structure.)
There are organization hubs that are "denomination-like" within which consensus is reached about interpretation of various points of Islamic law, called Madhhab, which are usually translated as "schools" (in a sense similar to "schools of thought"). But, the predominant "school" of Sharia law interpretation implemented, and the institutional manner in which this happens, varies considerably.
This answer's discussion addresses situations where the whole of Sharia law is applied. But in many countries (e.g. India and Israel) Sharia only has legal effect in matters of personal status (e.g. marriage, divorce, child custody, inheritance) and is only effective in situations when everyone affected is a Muslim. In general, the institutional and procedural implementation of Islamic law is going to vary from Afghanistan to Turkey to Saudi Arabia to Iran, for example, far more than the substantive pronouncements do. In some places there are separate Islamic law courts or legal systems, while in others, Islamic law is integrated into a state run comprehensive judicial system.
One historically common way to manage Islamic law was for someone who wanted to resolve an issue to go to an Islamic law scholar for a fact specific legal opinion (fatwa) and then to have that opinion enforced privately with that legal blessing, rather than through a governmental agency (much like the legal system in early medieval Iceland). If necessary, this legal scholar will act as a judge as well, but there will generally not be legally trained lawyers acting as advocates for the parties, and often there will be little or no opportunity to appeal this person's decisions. When operating in the form of a judicial proceeding the process bears some similarity to arbitration proceedings in Western legal systems.
But, early Islam did not have a separation of church and state and where the state was strong, implementation of Islamic law on a comprehensive basis was part of the general duties of the political leadership in any particular place.
Cultural Traditions Whose Status As Islamic Law Is Disputed
Many Muslim communities have cultural traditions which may even be ascribed to Islamic law. The most notable of these is honor killing. There is dispute between different Islamic scholars over whether this is justified by Islamic law. Some Islamic authorities say it is authorized by Islamic law. Other authorities vehemently deny this claim and say that no Islamic law authority supports it.
Many of the most controversial practices found in Islamic countries (another is female genital mutilation as noted in the link above) are in this disputed category, so whether they would be permitted or required in a place adopting Sharia law depends upon the positions of the influential voices on the meaning of Islamic law in that place.
Realistically, any place that adopts Sharia law will probably find that at least some local cultural practices are part of Sharia law, even though Islamic authorities in other areas or other schools of thought would disagree.