Mexico's Senate gave general approval on Monday to legislation laying out expanded powers for energy regulators, part of the fine print needed to implement a constitutional reform that overhauls the oil, gas and electricity sectors. Senators must still debate reservations to the regulatory legislation, which is likely to last into the night. The legislation forms part of the so-called secondary laws needed to flesh out the opening of the energy market, which is the centerpiece of the government's reform agenda. Once the reservations have been voted on in the Senate, the focus will move to the lower house of Congress, which is already debating the secondary laws passed by the upper chamber.