"Ser responsabilizado" is passive voice, and it would mean that someone would blame you for something, whether you did it or not.
- A mi hermano lo responsabilizaron de haber atacado al policía, pero él no estaba en ese lugar.
My brother was blamed for attacking the policeman, but he was somewhere else.
EDIT: This sentence was not using "Ser responsabilizado". This is the sentence I should have written:
- Mi hermano
fue responsabilizado por haber atacado al policía, pero él no estaba en ese lugar.
In this case "responsabilizarse" is a better option to talk about someone who actively assumes responsibility for something.
- Si no te responsabilizas de tus actos, nunca voy a confiar en ti.
If you don't assume responsibility for what you do, I'll never trust you.
- Si no enseñas a los niños a responsabilizarse de sus tareas en la casa, siempre van a depender de ti.
If you don't teach your children to be responsible of their chores, they will always depend on you.