Do you need to relate geography to law? Are you writing a reference for someone else, or asking a teacher to write a reference for you?
There is no particular relationship between law as an academic discipline and geography as an academic discipline. In the practice of law, things that may be studied in geography, such as natural resources, environmental conditions, climate change, transport systems, international boundaries, and so on might be relevant. Human demographics may be relevant to human rights law, especially on the subject of refugees, and to development finance and so forth. Climate factors and aspects of physical geography may be relevant to environmental law.
If you are applying to study law, you don't have to show that other subjects you have studied relate to your proposed future studies.