For "sistema (processual) acusatório", use "adversarial system".
There are multiple definitions - click on the translation that matches your context.
an adversarial system is one where two sides disagree with, oppose and attack each other, especially in law and politics
In our adversarial system, defendants have a fundamental right to legal counsel.
involving people disagreeing, opposing, or arguing with each other
The tribunal must endeavour to conduct open adversarial proceedings-