what margin is required to override a veto by president
Or it can be limited, as in the legislative process of the United States, where a two-thirds vote in both the House and Senate may override a Presidential veto of legislation. A veto gives power only to stop changes, not to adopt them (except for the rare amendatory veto). Thus a veto allows its holder to protect the status quo. The concept of a veto body originated with the Roman consuls and tribunes.