from Wikipedia, the free encyclopedia

By marriage or affinity ( Latin affinitas "affinity") refers to a through marriage or partnering mediated indirect family relationship between non- biologically or legally unrelated persons. Those who are related by marriage to a person are called brother-in-law or sister-in-law ( plural : brothers-in-law, sister-in-law) and are generally also referred to as relatives by marriage . What sisterhood means and includes in detail is defined differently in legal and general linguistic usage.


In parlance, sisterhood is defined fluently. Only the siblings of the spouse or partner (but not the other relatives in law, such as mother-in-law , son-in-law and also cousins ​​and cousins ​​in law ) are referred to as brother-in-law or sister-in-law . In this respect, the corresponding English terms brother-in-law and sister-in-law are informative . Furthermore, distant by-laws are often called brother-in-law or sister-in-law , in particular the spouses or life partners of their own siblings as well as the siblings of a brother-in-law (who are related by marriage).

Furthermore, the usage of the language is still based on the establishment of a brotherhood through marriage. Before the opening of marriage for all , however, was just through a partnership (the legal basis for marriage of same sex couples in Germany from 2001 to 2017) by marriage to be justified. The closed civil partnerships and the resulting fraternities are of course still valid, even after the registered partnership or partnership as an alternative to marriage has become superfluous due to the full marriage in Germany . A similar development is underway in Austria .

In Germany, Austria and Switzerland the law basically only understands kinship as blood kinship based on ancestry that is mediated by birth, so that from a legal point of view, brothers-in-law and sisters-in-law are not related to one another; From a legal point of view, they are “related by marriage”. The sisterhood is established through marriage. Thereby the relatives of one spouse are bound to the relatives of the other by the bond of mutual affinity; two family associations are thus linked to one another, and not just for the duration of the marriage that binds them, but forever. This has been the case for ages and is justified today by the fact that the children of the (now dissolved) marriage with the father family and the mother family are blood relatives or are legally related and remain so and are consequently fully entitled to inheritance. The sisterhood cannot be annulled through divorce, at most through death . The marriage relationship is lifelong - unless a marriage is declared null and void; But then the sisterhood did not even come about from the beginning due to the lack of a valid marriage. The "ex-brother-in-law" or the "ex-mother-in-law" therefore does not exist. A new marriage relationship also establishes a new, additional relationship with the relatives of the new spouse, etc. So: The new mother-in-law (mother of the new wife) does not replace the first (mother of the first wife), she joins them. Given today's realities of divorce, one can “accumulate” many in-laws and innumerable brothers-in-law from the spouse's point of view. This is the spouse's point of view. It looks slightly different for the children. For the children of the first marriage, the divorce of their parents and the remarriage of the same with other new spouses means the following: They are related to the parents, full siblings, father family and mother family, and are related by marriage to the stepparent and his relatives and not entitled to inheritance. They are related to their half-siblings through the common parent and mutually entitled to inherit and are related by marriage through the new spouse of their parents, whereby the sisterhood as the lex minor relationship (because it does not include any inheritance entitlement ) pales behind the relationship ( lex maior ). This applies across the board, regardless of the community or household.

For Swiss law, Article 21 of the Civil Code (in force since January 1, 2007) regulates the relationship as follows: “(1) Anyone who is related to a person is in the same line as their spouse, their registered partner and related by marriage to the same degree. (2) The sister-in-law is not canceled by the dissolution of the marriage or the registered partnership that established it. "

For German law, § 1590, Paragraph 1, Sentence 1 of the German Civil Code ( BGB ) stipulates : “The relatives of one spouse are related by marriage to the other spouse.” Analogously, the legal fiction of Paragraph 11, Paragraph 2, Sentence 1 of the LPartG reads : “The relatives of a partner are considered to be with by marriage to the other partner. ”The relationship does not end - as is often assumed - with a divorce ; There is no such thing as an “ex-brother-in-law”, the relationship is lifelong unless a marriage is declared null and void.

Accordingly, only persons by marriage in a straight line are recorded, but not remotely related by marriage ( Schwippschwäger ). In the legal sense, there is no brother-in-law relationship with the spouse's or partner's brother-in-law or with the siblings and other relatives of a person in law by marriage.

In the legal sense, stepchildren are also not related to their stepparents but are related by marriage.


In Roman law ( Corpus Iuris Civilis ) as well as in biblical - Old Testament legal concepts, which functioned as valid law in many parts of Europe or in the European cultural area through medieval church law until well into modern times, no distinction was made between kinship and brotherhood : With the marriage of two people, a relationship between the two families analogous to blood kinship was established, which is why i. d. R. In-law marriages or siblings (which can mean the marriage of two sibling pairs as well as the marriage of a sibling by the same partner, e.g. after the death of the first spouse) were prohibited or only possible in special exceptional cases with an express dispensation . (Extra-marital) sexual relationships between in-law, brother-in-law, but also e.g. B. between stepparents and stepchildren were legally treated like incest . Although the General Prussian Land Law of 1794 lifted most of the marriage prohibitions with regard to brotherhood, the prohibition of marriage between in-laws and their children-in -law (e.g. after the death of the original spouse who established the in-law relationship) continued to exist.


The first example is a constellation in which both jurisprudence and the general public assume a brother-in-law. Anton and Bernd are brothers. Anton marries Claudia and Bernd is married to Dora . Dora's brother-in-law is then Anton ; Claudia's brother-in-law is Bernd . Consequently, Anton and Dora as well as Bernd and Claudia are related by marriage, which indirectly implies that (also in the legal sense) Dora is referred to as Anton's sister-in-law and Claudia is Bernd's sister-in-law . Only Claudia and Dora are not related by marriage, rather they are sister-in- law in Schwipp .

Example of the reach of brotherhood

German law extends the partnership to all relatives of the partner. Based on this example, this means that Anton's brothers-in-law and sisters-in-law are also, for example, Dora’s granddaughters, sons, parents and other ancestors . Who is a kinship by law results from § 1589 BGB.

The second example also makes it clear who is one of the brothers-in-law in a given civil partnership (see Section 1 LPartG) because - depending on the definition -

  1. a brother-in-law
    • the husband of his own sister,
    • the partner of one's own brother or
    • the brother of one's own spouse or partner
  2. a sister-in-law
    • one's brother's wife,
    • the partner of your own sister or
    • the sister of one's own spouse or partner

It follows:

For cases of marriage

Representation of brotherhood in marriage

Heidi has two brothers , namely Michael and Markus , and a sister Susi . Heidi now marries Jochen , who has a brother named Bastian .

So it applies

  1. brother in law
    • First sub-case: Susi , Markus and Michael's brother-in-law is called Jochen .
    • Second sub-case: Heidi's brother-in-law is called Bastian ; Jochen's two brothers-in-law are called Michael and Markus .
  2. sister in law
    • First sub-case: Bastian's sister-in-law is called Heidi .
    • Second sub-case: Jochen's sister-in-law is called Susi .

Bastian and Michael are not related by marriage, they are "only" brother-in-law . This also applies to Bastian and Markus as well as Bastian and Susi .

For cases of civil partnership

Representation of the brotherhood of registered civil partners

Nothing else applies to registered civil partnerships. This example is Hella S. a legal partnership with Cornelia S. a. Cornelia has a sister S. , Hella a brother Harald S. , who in turn lives in a civil partnership with Herbert F.

Then applies

  1. brother in law
    • First sub-case: Hella's brother-in-law is called Herbert .
    • Second sub-case: Cornelia's brother-in-law is called Harald .
  2. sister in law
    • First sub-case: The sister of Sister S. 's Hella , Harald's sister, however, Cornelia S .
    • Second sub case: Hellas sister's sister S. , Herbert's sister Hella .

Designations and degrees

The most common names for certain people by marriage are:

  • In-laws : father-in-law, mother-in-law (the parents of the spouse or registered partner), earlier: in- law for the father-in-law and wife -in-law or also in -law (!) For the mother-in-law.
  • Children -in-law : daughter-in-law (formerly: Schnur , Söhnerin , Söhnere (Swabian)), son-in-law (formerly: Eidam , daughter husband ), spouse or registered partner of one's own child
    • This also gives rise to the less frequently used term of the grandchildren -in-law (daughter-in-law / son-in-law), the spouse or partner of one's own grandchild
  • Brother / sister : see above
  • Stepparents : stepmother , stepfather
  • Stepchildren : stepdaughter , stepson
  • Opponents in law (parents) : the parents -in-law of their own child or the parents of the child-in-law
  • Schwipp-brother /sister-in- law : As above (siblings and spouses of brothers-in-law); but also in a broader sense for siblings, uncles and aunts of the child-in-law. or uncles and aunts of the husband. Occasionally also for the opposing parents-in-law.
  • The brothers-in-law's children are known as nephews and nieces.
  • Uncle / aunts in law are uncles and aunts of the spouse.

Line and the degree of sisterhood depend on the line and degree of relationship ( Section 1590, Paragraph 1, Clause 2 BGB). A straight line is descent of a person from another moment ( § 1589 of set 1 BGB), the side line when two persons only by a common third person descended ( § 1589 of set 2 BGB).

If one summarizes this with the rule of § 1589 sentence 3 BGB, it follows that the degree of sisterhood is determined according to the number of births mediating it. Father and son are related to the first degree and in a straight line. If the father's wife is not the mother of the son and has not adopted him either, then the son is related to the wife in the first degree and in a straight line with the wife.

The following graphic shows the relationship based on the family of the wife shown in black:

Schematic representation of the degree and line of pregnancy

Legal situation and legal consequences

Legal definitions of sisterhood and the legal rules based on them can be found in various national laws :


It should be emphasized that in accordance with Section 1590 (2) BGB and Section 11 (2) LPartG, a partnership once established does not end when the marriage or civil partnership on which it was founded is dissolved or divorced.

With a defendant or one of the parties in either a straight line or in the sidelines to 2 degrees by affinity are according to § 52 , para. 1, no. 3 CCP and § 383 1, no. 3, para. ZPO to refusal of the certificate authority. Thus certain rights arise from the brotherhood; one can not only refuse to testify with regard to a brother-in-law in court , but B. also be a “biased person” within the meaning of Section 6 (4) of the Vergabeverordnung (VgV).


Art. 21 ZGB

1) Anyone who is related to a person is related by marriage to his or her spouse [ or their registered partner ] in the same line and to the same degree.
2) The brotherhood is not broken by the dissolution of the marriage [ or the registered partnership ] that established it.
(In [] = version according to the PartG , which came into force on January 1, 2007.)


Article 40 of the Austrian Civil Code specifies:

Family means the first parents with all their descendants. The connection between these people becomes kinship; but the connection which arises between one spouse and the relatives of the other spouse is called brotherhood.

Sisterhood in ethnology and sociology

In ethnology , marriage is examined on the basis of the numerous, often complicated, exogamy rules of clans .

From a sociological point of view, "marriage" in the upper class (especially in the nobility ) was an important mechanism for an economic / political alliance between two clans . In the case of a widespread relationship and sisterhood, the rights to refuse to testify (see above) could also be of particular relevance.

See also


  • Claude Lévi-Strauss : The elementary structures of kinship (=  Suhrkamp-Taschenbuch Wissenschaft . No. 1044 ). 3. Edition. Suhrkamp Verlag, Frankfurt am Main 2009, ISBN 978-3-518-28644-9 (French: Structures élémentaires de la parenté . Translated by Eva Moldenhauer , first edition: 1948, Lévi-Strauss, 1908–2009, was an ethnologist, founder of the ethnological Structuralism and formerly representative of an ethnosociology ).
  • Ruth Gall: Problem case mother-in-law. Together with your partner out of the crisis. Goldmann, Munich 1999, ISBN 3-442-15009-4 .

Web links

Wiktionary: Schwager  - explanations of meanings, word origins, synonyms, translations
Wiktionary: sister-in-law  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. PrALR on marriage (PDF; 416 kB)
  3. ^ Friedrich von Thudichum: History of the German private law . 1894 ( limited preview in Google Book search).