Both parties do this although the Republicans have arguably taken it to new heights, or lows, depending on your point of view. Courts have been reluctant to get deeply involved in such disputes, often taking the stance that with certain egregious exceptions, redistricting is an inherently political process and not so much a legal one.
Parties compete to win control of government precisely to draw political boundaries for their own benefit. But courts do occasionally step in and force the legislative branches to make changes. We just saw an example of this in Michigan.
Detroit — Michigan must redraw legislative and congressional districts for the 2020 election because current maps drawn by Republicans represent a political gerrymander “of historical proportions,” a three-judge federal panel ruled Thursday. The blockbuster ruling — which a legislative leader said Republicans will appeal to the U.S. Supreme Court — requires Michigan to conduct special state Senate elections for certain seats next year, cutting in half the four-year terms that current lawmakers are now serving.
The “predominate purpose” of the redistricting plan approved by the Michigan Legislature in 2011 “was to subordinate the interests of Democratic voters and entrench Republicans in power,” said the unanimous decision written by U.S. Circuit Judge Eric Clay, an appointee of Democratic President Bill Clinton.