Ulpian: Roman Family Law

By Joseph Manning

I’ve mentioned the Roman pater familias briefly in another post.  This is a technical legal term of art that does not simply mean “father;” for example, to be a pater familias it was unnecessary to be a father in fact. Under Roman law a pater familias was endowed with patria potestas.  The patria potestas is the legal power of the father — it was a bundle of rights generally concerning property and the lives of those who were in potestate (under the power of the pater).

In a family consisting of a 80 year old man, his 60 year old son, his 40 year old grandson, his 20 year old great-grandson, and a newborn great-great-grandson, the only pater familias is the 80 year old; he owns all property and has power of life or death over all those under his power.

In Rome one was either sui iuris (under their own power) or alieni iuris (under another’s power).  All patres familias were sui iuris.  But not everyone who was sui iuris was a pater familias.  Women could not be patres familias but they could be sui iuris if their pater died or if they were emancipated.

Who had patria potestas and over whom did they have it?  The oldest male in an agnatic family tree exercises the power over all agnatic descendants and all slaves.  Agnatic relationships are not difficult.  They are reflected in our English system of last names with only only exception.  You are agnatically related to everyone who shares your last name — with the exception of wives; use the maiden name for this purpose.


The power over life and death was called vitae necisque potestas.  Roman birth control basically consisted of infanticide and this was mostly done by exposing newborns to the elements.  This practice was relatively wide-spread and uncontroversial.  Even the legendary founders of Rome were the product of a failed exposure. Unlike other societies in antiquity the practice was unrelated to religious ceremony.  Human sacrifice was forbidden; though that ban was mostly symbolic since the practice was rare anyway.  Rather, infanticide stemmed from recognizing harsh economic realities and different societal values than we have today.  It was more compassionate to kill an infant rather than to raise it in poverty; also, the survival of a new addition to the familia could endanger the survival of the rest.

What about deformed infants?  The Twelve Tables commanded “an obviously deformed child must be put to death.”  It’s hard to imagine that significantly ill or deformed infants would be allowed to live — but I think minor deformities might have been tolerated.

Did the power of life and death extend into the child’s adulthood? 

Yes and no.  Probably, in the early history at the legal theoretical level, a pater could summarily execute anyone in his potestas for any reason.  Sociologically and practically, this never happened.  Also, definitely by the time of Augustus if not earlier, exercising this kind of power had been severely restricted only to a few instances.  For example, here are some of the requirements a father had to meet under the Lex Iulia before he could justify killing a daughter.

He had to have 1) personally witnessed, 2) her committing adultery, 3) in flagrante delicto (not before/after), 4) only in his or his son-in-law’s home, 5) and he had to kill both daughter and lover (not one or the other), 6) and he had to do so immediately.  In this way the power of life or death doesn’t really seem to be much of a power at all.  It much more resembles a heat of passion defense in our modern law.  Requirement 4 shows that the passion resulted as much from the invasion into his domus by a stranger (like burglary) than anything else.

Also, Ulpian wrote:  “Inauditum filium pater occidere non potest, sed accusare eum apud praefectum praesidemve provinciae debet.”  “Without a hearing a father can not kill a son, but should accuse him before a prefect or provincial governor.”  These kinds of hearings were mostly used only in cases when a son was plotting a father’s death or was plotting to rebel against the State.


W. V. Harris, “Child-Exposure in the Roman Empire,”  The Journal of Roman Studies, Vol. 84 (1994), pp. 1-22.

H. Bennett, “The Exposure of Infants in Ancient Rome,” The Classical Journal, Vol. 18, No. 6 (Mar., 1923), pp. 341-351.

R.P. Saller, Patriarchy Property and Death in the Roman Family, (Cambridge 1994).

B.W. Frier & T.A.J. McGinn, A Casebook on Roman Family Law,  (Oxford 2004).


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