The House select committee investigating the January 6 insurrection at the US Capitol has received a cache of emails belonging to Donald Trump’s lawyer, John Eastman, federal court documents filed on Tuesday show.

The 101 emails were released to the committee after Judge David Carter ruled in federal court in California last week that Eastman, a hard-right supporter of the former US president, had not made a sufficient claim to attorney-client privilege.

The cache of documents, sent between 4 and 7 January 2021, contains extensive communications between Eastman and others about plans to obstruct the certification of Joe Biden’s victory in the 2020 presidential election.

These included proposed efforts to push Trump’s former vice-president, Mike Pence, to reject or delay counting electoral college votes and weaponizing false allegations of voter fraud in numerous state lawsuits.

In one email, which includes a draft memo for Trump’s personal lawyer, Rudy Giuliani, recommending Pence reject some states’ electors during the 6 January congressional meeting, Carter ruled for disclosure as the communications were being used to plan criminal activity.

“The draft memo pushed a strategy that knowingly violated the Electoral Count Act, and Dr Eastman’s later memos closely track its analysis and proposal,” the ruling says. “The memo is both intimately related to and clearly advanced the plan to obstruct the Joint Session of Congress on January 6, 2021.”

Neither Trump nor Eastman have been charged with crimes relating to 6 January and the order on Eastman’s emails was made in civil court.

Others references to emails in the judge’s ruling allude to other plans Eastman was involved in.

“In a different email thread,” Carter writes, “Dr Eastman and a colleague consider how to use a state court ruling to justify Vice-President Pence enacting the plan. In another email, a colleague focuses on the ‘plan of action’ after the January 6 attacks, not mentioning future litigation.”

The sprawling select committee investigation, chaired by the Democratic congressman Bennie Thompson from Mississippi, has interviewed more than 800 people as part of its investigation into the events on January 6.

On Tuesday, Thompson confirmed that Ivanka Trump, the former president’s daughter, had appeared before the committee, marking the first time a member of the immediate Trump family had appeared.

Reports indicated her testimony lasted about eight hours. The testimony followed an appearance before the committee by her husband, Jared Kushner, the previous week.