I happened to come across the opinion that propounds that head covering for women is not part of the Shariah. I am interested in knowing the reasoning behind.
We believe that head covering is not the part of the Shari'ah directives regarding etiquette of gender interaction. That certainly does not mean that proponents of this view aim at making women throwing off their head coverings. Rather it is only to identify the Shari'ah directives in this regard. The dress code that the Arabs would follow had not been introduced by the Shair'ah rather it was in currency before the advent of Islam. The Shari'ah only corrected some undesirable practices like carelessness in covering chests by women. Therefore, the label of the Shari'h should only be confined to those directives that the Qur'an introduced not the previous practices.
Shari`ah does not bind women to wear a full leaves shirt rather women, owing to their modest nature and custom based on the moral values, do so. The same is the matter of the head covering. It can be purely an adherence to the cultural customs or demand and a requirement of modesty. Now one can argue that women should not let go of head coverings on any moral or cultural ground but they cannot include it in the Shari'ah directives.
Usually, the following verse is presented to prove that head covering is essential for women to wear.
يَا أَيُّهَا النَّبِيُّ قُل لِّأَزْوَاجِكَ وَبَنَاتِكَ وَنِسَاء الْمُؤْمِنِينَ يُدْنِينَ عَلَيْهِنَّ مِن جَلَابِيبِهِنَّ ذَلِكَ أَدْنَى أَن يُعْرَفْنَ فَلَا يُؤْذَيْنَ وَكَانَ اللَّهُ غَفُورًا رَّحِيمًا
O Prophet! say to your wives and your daughters and the women of the believers that they let down upon them their over-garments; this will be more proper, that they may be known, and thus they will not be given trouble; and Allah is Forgiving, Merciful.
The world Jalabeeb is often taken as head coverings. Regardless of what does the verse requires the Muslims women to do, it only pertains to extraordinary circumstances. This is evident from the context and explicit indication in the text. This is a point acknowledged by almost all the jurists of Islam. The context, in which the verse occurs and the reason it gives for the directive (see underlined words) does not match the ones the Muslims scholars give in order to render it a Shari'ah directive.
Please refer to the following discussions /articles for detail. Regarding Head-Covering for Muslim Ladies , Should a Woman Cover Her Head?