Popov v. France, ECtHR, Applications Nos. 39472/07 and 39474/07, Judgment of 19 January 2012

The European Court found that whilst mutual enjoyment by parent and child of each other’s company constitutes a fundamental element of family life, it cannot be inferred from this that the sole fact that the family unit is maintained necessarily guarantees respect for the right to a family life, particularly where the family is detained.

https://hudoc.echr.coe.int/eng?i=001-108710