Nikah is not only an agreement between two people. It has social and familial results. The traditions and the rules of the society play a role on the marriage. Therefore, no nikah can be performed secretly.
Islamic and civil marriages are not two distinct concepts. Civil marriage is performed under the supervision of civil authorities. Islamic marriage similarly requires supervision, and the primary supervisor is sought to be the bride’s father. If the father and other male relatives renounce the duty of supervision or object to the marriage without Islamic basis, the supervisor becomes the civil or other lawful authority.
Islamic marriage has the additional condition of “mehr” which must be supervised while being determined and written down.
An Islamic marriage (nikah) can be performed under the following conditions:
1- Both sides must be free of obstacles to marry and have legal capacity.
2- Both sides or their guardians or representators must be present at the same time during the proposal and acceptance.
3- The prohibitions of marriage in verses An-Nisa 23,24 and An-Noor 3, which include the prohibitions about blood and milk kinship must be observed.
4- There must be no other conditions demanded by any of the the sides which may prevent the nikah .
5- The bride and the groom must have reached the age of maturity (this may come true at the same age or after the puberty. See: http://www.islamandquran.org/?p=3043)
6- In compliance with the verses An-Noor 24:3,5 ; Al-Maidah 5:5 and An-Nisa 4:24 both the bride and the groom must be chaste. See also: http://www.islamandquran.org/?p=2711
A nikah is valid from Islamic point of view under the following conditions:
1- Supervision and testimony : See the explanation below
2- Consensual agreement to marry: No girl/boy or woman/man can be wed against her/his will.
3- Announcement: Marriages, especially the ceremony of nikah is performed in order to announce the marriage. Therefore, nikah must be announced to everybody.
4- Mehr : Legal Share of Bride is given to the bride by the groom. It is not a condition for the nikah to be valid, but the right of mehr arises as a natural result of the nikah for the bride. See http://www.islamandquran.org/fatwas/what-is-mahr.html
The Messenger of Allah says:
“There is no marriage without a supervisor (Wali) and two reliable witnesses. A marriage performed without these is void. If they couldn’t agree, the authorized officials are the supervisor.” (Abu Dawood, Nikah/Marriage, 20; Tirmidhi, Nikah/Marriage, 14; Ibn Majah, Nikah/Marriage, 15; Ahmad Ibn Hanbal, Musnad, 6/66)
A supervisor should be the woman’s father, grandfather, son, brother, uncle, etc. respectively. If they are not found or refuse to perform their duty, the authorized official becomes the supervisor. The duty of the supervisor is investigating the groom-to-be whether he fulfills the conditions mentioned above. For example, unchastity of a boy or man can be witnessed more easily by another man than by a woman, because men have wider access to men-exclusive environments. Another example could be that the maturity of a boy and whether he could maintain a family can be witnessed more easily by an elder man. The supervisor can object to the marriage only if the conditions mentioned in the Qur’an are not fulfilled by the groom-to-be. Any other objection is considered groundless regarding the marriage. If the supervisor insists on a groundless objection, he loses his right to supervise. Thus, the authorities in charge become the supervisor.
Today, there is no country in the world that permits marriages without supervision. Officials of the municipalities, churches, synagogues are examples of authorized supervisors for marriage. Prophet Muhammad (pbuh) did not require walee for men and sufficed the approval of walee for women, which eases marriage, protects women’s rights and lets happy families be established.