ولي-Guardian

Opinion that the walli is not a condition: Abu Hanifa, Ashaa'bi, Muhammad ibn Shahab Azzuhri. Their evidence is that a woman is allowed to sell and buy products, then she is also allowed to give herself in marriage too. But they all agreed that she must be كفء equal compatible in status i.e: age, dialect, country, etc... 

 أما ما دلة عليه السنة فلا حجة في احد خالف قوله السنة As for what has been proven by the Sunnah then there is no excuse from anyone whom goes against the sayings of the Sunnah

 قَدْ عَلِمْنَا مَا فَرَضْنَا عَلَيْهِمْ فِي أَزْوَاجِهِمْ قال قتادة: إن مما فرض الله عليهم أن لا نكاح إلا بولي وشاهدين. (تفسير الطبري) وقال الطبري في تفسيره: وهو أنا فرضنا عليهم أنه لا يحل لهم عقد نكاح على حرة مسلمة إلا بولي عصبة وشهود عدول، ولا يحل لهم منهن أكثر من أربع. وَإِذَا طَلَّقْتُمُ النِّسَاءَ فَبَلَغْنَ أَجَلَهُنَّ فَلَا تَعْضُلُوهُنَّ أَن يَنكِحْنَ أَزْوَاجَهُنَّ إِذَا تَرَاضَوْا بَيْنَهُم بِالْمَعْرُوفِ  وَإِذا طَلَّقتُمُ النِّساءَ فَبَلَغنَ أَجَلَهُنَّ فَأَمسِكوهُنَّ بِمَعروفٍ أَو سَرِّحوهُنَّ بِمَعروفٍ It has been anamously agreed by the Scholars of Tafseer that the one who is addressed in this verse is the Awliyaa (Wallies) Aiesha said that there are four types of marriages, the one in which a man marries off his daughter or sister off to another man based on a mahr, after mentioning all the other types of marriages she said that the Prophet ﷺ abolished all of them except the first one. Sahih al Bukhari.

 عمر قال لا نكاح الا بولي ما كان أشد ناس بين أصحاب الرسول من علي ابن ابي طالب في زواج بغير ولي حتى كان يدرب عليه

 ابن عباس قال لا نكاح الا بولي أو سلطان مرشد (rightly guided imam) These Athar are found in Sunnan abi Shayba or Buyhaq

Who are the wallie's in order known as the (العصبة):

1-The Father

2-Grandfather fathers side

3-Her brother with the same mum & dad as her

4-Her brother from her father (not her original father)

5-Her brothers son (brother from the same mother and father as her)

6-Nefew from her brother who has the same father as her

7-Her uncle who has be same mum & dad as her father paternal. 

8-Her uncle who only has the same father as her dad 

ابن عم-9- her cozen from the fathers side her fathers brothers son. Her uncle must have the same mum and dad as her father.

10- her cozen from the fathers side her fathers brothers son. Her uncle must have the same dad as her father.

Note: that the cozen can only be a wallie in two cases: 1- if she is in a situation that the father, brother, or uncle are not available and they authorize the couzen to be the wallie.

2-That all these Wallie's are not present due to death so it is permissible in this case for the cozen to be a wallie, baring in mind that some of the Scholars disagreed on this.

Al Hafiz ibn Abdul Bar in al Astadhkār:

The Scholars differed in two opinions is the Walli from the linage (paternal & maternal) or the Asabah (paternal), and the Asabah is the majorities opinion.

If the father is alive but not present there is two opinions: 1-It moves over to the closest (grandfather etc) Abu Hanifa, Malik, & Ahmad and one of the opinions of ashaffae 

2-It moves on to the Sultan (Imam or ruler etc) this the common opinion of Ashaffaee.

In regards to the father absence is divided into two categories absences that is cutoff or absence that is not cutoff. Absence that is not cutoff means that he is able to be in contact with via letters, email, or phone calls. Furthermore one must be patient until he replies Al Hassan said: he must be patient like the patience of Ahul Al Kahf. 

Ashaffai says: Marriage without a guardian is an automatic separation (fiskh) whether it's before consummation or after it, doesn't matter for how long, nor do they inherit from each other.

  عن الشعبي  قال : ما كان أحد من أصحاب النبي صلى الله عليه وسلم أشد في النكاح بغير ولي من علي كان يضرب فيه .

 

وعن عكرمة بن خالد  قال : جمعت الطريق ركبا ، فجعلت امرأة منهن ثيب أمرها بيد رجل غير ولي فأنكحها ، فبلغ ذلك عمر  ، فجلد الناكح والمنكح ورد نكاحها رواه الشافعي  والدارقطني

قالوا أهل الرأي: وليس الولي من أركان صحة النكاح ، بل من تمامه . وقال الأوزاعي وأبو يوسف ومحمد : تتوقف صحة النكاح على إجازة الولي. وقال أبو حنيفة : لا يشترط في الثيب ولا في البكر البالغة ، بل لها أن تزوج نفسها بغير إذن وليها.