The laws of Malaysia can be classified into two types of laws, which are written law and unwritten law. Written laws are the Malaysia’s most important source of law. These written laws are made up of Federal Constitution, Acts of Parliament and Enactments, and subsidiary/delegated legislation.
Unwritten laws are laws which are not enacted by the legislature (Parliament and State Assemblies) and not found in the constitution, both federal and state. This is known as the English common law and the rules of equity. In case, if there is no law governing a particular circumstance, Malaysian case law may apply. If there is no Malaysian case law, English case law can be applied in accordance with the Civil Law Act 1956 (Revised 1972) only in the absence of local statues on the particular subject matter. It is mean that the common law and the rules of equity can be modified and should not follow the same law as administered in England. Common law and the rules of equity can be developed and amended according to the local needs. S3(1) of the Civil Law Act 1956 statutorily provides that only the part of the English Law that is suited to the local circumstances are to be applied : I. West Malaysia - the English common law and the rules of equity and statues of general application in England as 1 December 1951. II. Sabah – the English common law and the rules of equity and statues of general application in England as at 1 December 1951. III. Sarawak – the English common law and the rules of equity and statues of general application in England as at 12 December 1949.
English laws subsequent to the said dates are not binding but of persuasive authority.
According to Prof. Mark Cammack, Southwestern University, Islamic law is not a legal system, but a legal tradition, much like the common or civil law tradition. It is a set of related beliefs, attitudes, and practices regarding the necessary components of a legal system, including the scope and purposes of the law, the manner in which law is created or discovered, the identity and function of legal actors, and the manner in which law is learned, implemented, developed and adapted.
The main source of Islamic law is the Quran, as it contains all the fundamental directives and instructions of God. The second source of Islamic law is the Sunnah. Sunnah is an Arabic word which means “Method”. Sunnah refers to the actions, statements, and agreements of the Prophet Muhammad. While Ijma (consensus of opinion of scholars) and Qiyas (laws derived through analogical deduction) are the dependent sources of Islamic law
In Malaysia, Islamic law is enacted under the Federal constitution. The state legislatures have the power to administer Shariah law to states but it is limited to family law, personal matter and such criminal law provided by Federal law. Ninth Schedule, List II stated that punishment of offences by Shariah Court is limited to those professing the religion and in respect of offences conferred by federal law. However, the constitution Amendment Act 1988 was added new clause which is Art 121(1A). It is stated that high court and inferior court established by federal law shall have no jurisdiction of the Shariah Courts. Moreover, parties before Shariah Court must be a muslims. Shariah has no jurisdiction of one of the parties is non-muslims.
Therefore, English common law and Islamic law are two suitable laws that can be applied in Malaysia. Populated by the three major races which is Indian, Malay and Chinese and also with difference religion and belief, that two laws are very suitable to practise in Malaysia. Basically, jurisdictions of Shariah Court are about marriage, divorce, family and small estate solutions. For an example case on divorce, in Arabic it is called “talak”. Talak is never encouraged in Islam, no one can be forced to lead a miserable life in a marriage. Therefore, if a marriage is clearly failing, and its ideals already seem farfetched, more so when it has been a source for hardship, cruelty, quarrels, sufferings, and arguments then the better solution is a separation. As long as both parties are muslim, the case is under Shariah Court.
While, case like a criminal, business partnership and others are based on English common law. No matter the parties muslim or non-muslim, case like that will judge base on English common law.

Reference
Mumtaj Hassan, Khuzaimah Mat Salleh, Zuryati Mohamed Yusoff. (2003). Undang-undang Perniagaan di Malaysia. Universiti Utara Malaysia.
Cammack. M. Islamic Law. Retrieved December 7, 2011, from http://www.lfip.org/laws827/link02-islamiclaw.htm