Chief Justice John G. Roberts Jr. has received more than a dozen judicial misconduct complaints in recent weeks against Brett M. Kavanaugh, who was confirmed as a Supreme Court justice Saturday, but has chosen for the time being not to refer them to a judicial panel for investigation.

A judge on the U.S. Court of Appeals for the D.C. Circuit — the court on which Kavanaugh serves — passed on to Roberts a string of complaints the court received starting three weeks ago, said four people familiar with the matter.

That judge, Karen LeCraft Henderson, had dismissed other complaints against Kavanaugh as frivolous, but she concluded that some were substantive enough that they should not be handled by Kavanaugh’s fellow judges in the D.C. Circuit.

In a statement Saturday, Henderson said the complaints centered on statements Kavanaugh made during his Senate confirmation hearings.

Under the law, “any person may file a misconduct complaint in the circuit in which the federal judge sits,” she said in the statement. “The complaints do not pertain to any conduct in which Judge Kavanaugh engaged as a judge. The complaints seek investigations only of the public statements he has made as a nominee to the Supreme Court of the United States.”

The complaints were handed over as scrutiny of Kavanaugh was intensifying amid allegations that he sexually assaulted a girl when the two were in high school. Kavanaugh has vehemently denied the allegations, as well as two other accusations of improper behavior.

People familiar with the matter say the allegations made in the complaints — that Kavanaugh was dishonest and lacked judicial temperament during his Senate testimony — had already been widely discussed in the Senate and in the public realm. Roberts did not see an urgent need for them to be resolved by the judicial branch while he continued to review the incoming complaints, they said.

The situation is highly unusual, said legal experts and several people familiar with the matter. Never before has a Supreme Court nominee been poised to join the court while a fellow judge recommends that misconduct claims against that nominee warrant review.

Roberts’s decision not to immediately refer the cases to another appeals court has caused some concern in the legal community. Now that he has been confirmed, the details of the complaints may not become public and instead may be dismissed, legal experts say. Supreme Court justices are not subject to the misconduct rules governing these claims.

“If Justice Roberts sits on the complaints, then they will reside in a kind of purgatory and will never be adjudicated,” said Stephen Gillers, a professor at New York University Law School and an expert on Supreme Court ethics. “This is not how the rules anticipated the process would work.”

The Senate voted to confirm Kavanaugh on Saturday afternoon.

Kathleen Arberg, a spokeswoman for the Supreme Court, declined to comment, citing judicial rules requiring confidentiality for misconduct complaints.

Even if Roberts had referred the complaints, it may have had no practical effect. Referring the case to another appeals court could make the complaints public. But, it typically takes months for a judicial panel to decide the veracity of misconduct complaints, so these would not have been resolved by the time the Senate voted on Kavanaugh’s nomination.

Roberts, an appointee of President George W. Bush, has for many years hired Kavanaugh clerks to work for him at the Supreme Court. Bush credits Kavanaugh in his book with helping him choose Roberts for the high court when Kavanaugh was a White House lawyer.

Normally, misconduct complaints are confidential and do not become public until they are fully investigated and concluded.

Most of these complaints center on Kavanaugh’s answers about his work in the Bush administration, according to people familiar with them. They also accuse Kavanaugh of lacking judicial temperament in his partisan comments about Democrats, the people said.

None of the complaints deal with the allegations made against Kavanaugh by Christine Blasey Ford, who said he had sexually assaulted her when they were teenagers.

It is rare for a misconduct complaint against a judge to get as far as the chief justice. The chief judge of a circuit court normally reviews complaints against judges in his or her circuit. Most are dismissed because they lack a factual basis to make such a claim or are simply disagreeing with a judge’s decision.

Henderson, whom President George H.W. Bush nominated to the bench, stepped in to review the complaints against Kavanaugh because Chief Judge Merrick Garland — whose nomination to the Supreme Court by President Barack Obama was blocked by Senate Republicans — recused himself from the matter.

The way the complaints against Kavanaugh are being dealt with is unusual, because Henderson concluded that the D.C. Circuit cannot properly handle them , and referred them to the chief justice. This is done only in exceptional circumstances, under the judiciary’s rules on misconduct.

Kavanaugh is a member of the D.C. Circuit Judicial Council, which normally rules on misconduct allegations in that court.