WASHINGTON, July 2 (Reuters) - When the U.S. Supreme Court issued its ruling defending the Federal Reserve from political interference, it not only prevented President Donald Trump from firing one of the central bank's governors, it also highlighted growing unease among the justices about the use of their ever-expanding emergency docket.

Three of the four conservative justices who dissented in Monday's ruling involving the Fed's Lisa Cook also criticized the five justices who were in the majority for making such a consequential decision using the court's procedure designed for emergencies — and short-circuiting lower courts in ​the process.

That prompted Chief Justice John Roberts to defend the landmark action using this pathway in the Cook case as a matter of "prudence" on which people can disagree. Roberts authored the 5-4 ruling, joined by fellow conservative Justice Brett Kavanaugh and the court's three liberal justices.

Critics for years ‌have raised concerns about the court's increasing willingness to decide major issues using the emergency docket — also called the "shadow docket" or "interim docket" — saying it lacks transparency and accountability to the public, and gives short shrift to complex and high-stakes legal disputes.

This docket lets the justices render decisions before lower courts have decided the legal merits of a case, generally bypassing the Supreme Court's regular procedures that involve extensive briefing, oral arguments, months of deliberation and lengthy written rulings. Emergency orders typically are made rapidly and often provide no explanation or rationale.