WASHINGTON (AP) — The Supreme Court has dealt a huge blow to efforts to combat the drawing of electoral districts for partisan gain in a ruling that could embolden political line-drawing after the 2020 census. On the court’s final day of decisions before a summer break, the conservative justices ruled Thursday that federal courts have no role to play in the dispute over the practice known as partisan gerrymandering. The decision affects cases in Maryland, Michigan, North Carolina, Ohio and Wisconsin.