Most modern legal systems formally endorse the presumption of innocence, but how it's actually implemented varies by legal tradition. Common law systems (like the US and UK) put the entire burden of proof on the prosecution and typically require a high threshold like "beyond reasonable doubt." Civil law systems (common across much of Europe) often give judges a more active, investigative role in gathering facts before trial, which can change how a presumption of innocence plays out in practice even when it's equally codified on paper.