The Supreme Court has upheld the use of a controversial drug that has been implicated in several botched executions.

The justices on Monday voted 5-4 in a case from Oklahoma that the sedative midazolam (mih-DAZZ-oh-lam) can be used in executions without violating the Eighth Amendment prohibition on cruel and unusual punishment.

The drug was used in executions in Arizona, Ohio and Oklahoma in 2014 that took longer than usual and raised concerns that it did not perform its intended task of putting inmates into a coma-like sleep.

The Supreme Court began meeting Monday for the final time until the fall to decide three remaining cases and add some new ones for the term that starts in October.

The court decided its two blockbuster cases last week by declaring the right of same-sex couples to marry in all 50 states and upholding a critical part of the health care overhaul.

The two remaining cases are about state efforts to reduce partisan influence in congressional redistricting and costly Environmental Protection Agency limits on the emission of mercury and other toxic pollutants from power plants.

The justices also could add important cases for next term on abortion, affirmative action and the power of unions that represent government workers.

Here are more details about the two remaining undecided cases:

  • Independent redistricting commissions: Roughly a dozen states have adopted independent commissions to reduce partisan politics in drawing congressional districts. The case from Arizona involves a challenge from Republican state lawmakers who complain that they can't be completely cut out of the process without violating the Constitution.
  • Mercury emissions: Industry groups and Republican-led states assert that environmental regulators overstepped their bounds by coming up with expensive limits on the emissions of mercury and other toxic pollutants from power plants without taking account of the cost of regulation at the start of the process. The first-ever limits on mercury emissions, more than a decade in the making, began to take effect in April.