What is the legal ruling on dealing with a brother who does not pray, disobeys his mother, and is suspected of drug abuse, given that the father refuses to use force and limits himself to advising? And what is incumbent upon the questioner towards her brother?

Your brother is committing grave sins, including abandoning prayer and disobedience to parents. To deal with him, we recommend the following:

Firstly: Be patient with him and supplicate for his guidance, for the supplication of a parent is answered.

Secondly: Continue to advise him with wisdom, gentleness, and good admonition.

Thirdly: If advice does not work, consider the matter of shunning him, while taking into account the benefit, as it might increase his stubbornness.

Fourthly: Your father should fulfill his role in advising and guiding. As for disciplining an adult with physical punishment, it is often not effective in our time.

Fifthly: If you have offered advice in the correct manner, you have fulfilled your duty, for enjoining good and forbidding evil is a collective obligation (fard kifaya).