Answer
Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Civil marriages in Western countries can be valid in Islam as long as they meet the basic conditions of Shari’ah, such as mutual agreement and no prohibited relationships. However, Muslims must ensure there are no Islamic reasons preventing the marriage, such as interfaith or foster relationships.
In this regard, Sheikh Faysal Mawlawi, the late Deputy Chairman of the European Council for Fatwa and Research, states:
What Makes a Marriage Valid in Islam?
The legal marriage which is done in European countries is regarded as a valid marriage in the Shari`ah as long as there is no legal reason in the Shari`ah against it.
This is because the basic condition in a valid marriage is the agreement of the couple, which is present in case of the civil marriage or court marriage. Also, announcement is usually implied.
As for the condition of two witnesses it is, according to some schools, required to guarantee that the marriage is announced, and this is achieved in a legal marriage.
As for the agreement of the guardian, it is an issue of disagreement among schools of Fiqh.
Shari’ah Reasons That Prevent Marriage
Therefore, the only condition which invalidates a court or legal marriage in the West is if there exists any reason which prevents marriage in the Shari`ah.
For instance, a Muslim is not allowed to marry his foster-sister, though this is permissible in European laws. (Likewise, a Muslim woman is not allowed to marry a non-Muslim and a Muslim man is not allowed to marry any non-Muslim other than a Christian or Jewish woman, though all types of inter-faith marriage are permitted in Western laws.)
Therefore, if a marriage is contracted between a Muslim and his foster-sister in a Western country, this marriage is not valid in Shari`ah as there is a reason which prevents marriage and it is haram for the concerned partners to engage in sexual intercourse.
If there is no Shari`ah reason to prevent the marriage, then the marriage done in a Western country can be regarded as a valid marriage in the eyes of the Shari`ah and can be accepted by the Shari`ah courts in Muslim countries.
This is the rule, particularly if the Muslim couples are of a European nationality or origin. However, if one or both of them hold nationality of a Muslim country, then they must make the marriage contract in a Muslim country [or register it with the appropriate consulate(s) so that the marriage is recognized abroad]. If, however, they make the contract in a non-Muslim country, then the marriage is still valid as long as there is no Shari`ah reason to prevent the marriage, yet they are sinful for not resorting to a Muslim court and accepting to apply non-Muslim laws instead.
As for the Shari`ah reasons that prevent marriage, they are as follows:
If the wife is one of the prohibited categories to marry in the Shari`ah including mother, daughter, sister, paternal and maternal aunts.
Foster-mother and foster-sister.
A Muslim man is not allowed to marry a married woman or a widowed or divorced woman who is still in her `iddah(waiting period) after being widowed or divorced. Only after the elapse of `iddah, marriage is permissible.
A Muslim is not allowed to have in marriage more than four wives at the same time, or to have two sisters in marriage at the same time, or to have a woman and her paternal or maternal aunt at the same time.
A Muslim woman is not allowed to marry a non-Muslim, and a Muslim man is not allowed to marry any non-Muslim other than a Christian or Jewish woman.
Explore related topics with the following links:
What Are the Conditions of Marriage in Islam?
Is Secret Marriage Allowed In Islam?
What Invalidates Marriage in Islam
Significance of Registering Marriage in the West
Getting the Wali’s Consent on Phone for Marriage: Valid?
Is Marriage Valid via Modern Means of Communication?
Allah Almighty knows best.