What is the ruling on a girl marrying without a guardian, on a misyar marriage, and on a mut'ah marriage?

A woman is not permitted to marry herself without a guardian (wali). Such a marriage is invalid by the consensus of the majority of scholars. If she does so, she is not subject to the hadd punishment for adultery, but rather to ta'zir (discretionary punishment), due to the differing opinion of the Hanafis who validate the contract without a guardian.

As for temporary marriage (zawaj al-mut'ah), it is a marriage for a specific period, and it is invalid and forbidden. Scholars have differed on whether it constitutes zina (adultery/fornication) that necessitates the hadd punishment. The majority holds that it is not zina necessitating the hadd due to the presence of a شبهة (semblance of a contract), but a severe ta'zir is obligatory. However, a weak opinion among the Shafi'is states that the hadd is obligatory because it is a abrogated form of marriage.

Informal marriage (zawaj 'urfi) takes various forms: 1. Marriage without a guardian or witnesses: This is invalid by the consensus of the imams, and the person who commits it deserves punishment, even if no hadd is applied due to the presence of a semblance of a contract. 2. Marriage with witnesses but without a guardian: This is invalid according to the majority. 3. Marriage with a guardian and two witnesses but without declaration: This is sound according to the preponderant opinion, even if it contains a Sharia violation due to the lack of public declaration.