Beyond the overarching protection of relevant fundamental rights (such as the fundamental right to freedom of research or the protection of life), research on and the possible use of germline therapy in Germany is largely regulated by the Embryo Protection Act (ESchG), a source of criminal law. The central function of this law is to protect embryos from misuse.

The ESchG defines germ cells in §8 para. 3: " Germ line cells, for the purpose of this Act, are all cells that lead of the egg and sperm cells to the resultant human being and, further, the egg cell from capture or penetration of the sperm cell until the ending of fertilisation by fusion of the nuclei. " Regarding germline therapy research, the ESchG prohibits so-called destructive embryo research, i.e., the explicit creation and subsequent discarding of embryos for research purposes.

In addition, Section 5 (4) of the ESchG prohibits any attempts to alter the genetic information of a germ cell as well as its use for fertilisation. Several procedures are exempt from this prohibition: the modification of genetic information on germ cells is permissible if the germ cell is located outside of a human body and is not used for subsequent fertilisation. Also permissible is the alteration of genetic information on a germ cell that has been taken from a deceased human or an embryo that has not developed further and will not be used for fertilisation. Finally, a modification of the genetic information of a germ cell is permitted if it occurs as an unintended side effect of vaccination, radiation, or chemotherapy.

Beyond this, the extent to which the ESchG permits research on the modification of germ cells of so-called tripronuclear embryos is disputed because of the way it was worded. It is also disputed whether the ESchG also prohibits the modification and subsequent use for fertilisation of precursor cells of germ cells artificially obtained during the process of reprogramming. Apart from these controversial cases of application, the ESchG generally limits further clinical research and application of germline therapy.