Are There Any Legalities Concerning Adoption?

The answer to that question depends on where you have adopted or decide to adopt from.

Road
Homeless animals can be taken home with no legal documents or paperwork. 

Animal shelter
Prior to adoption, you will be required to fill out a form where you will be asked about information such as name, address, number of people in the family, the income of each family member, number of pets at home, number of children at home, history of any addiction or illness, etc. After this, you will be matched or allowed to choose your pet. Before allowing a pet to be adopted, most shelters will visit the potential adopter’s homes to ensure that the pet is a perfect fit for the family. 

Foster family
Foster families do not require any legal documentation. However, like animal shelters, they may insist on a house visit prior to adoption.