A judge overseeing the upcoming second trial of former Trump campaign manager Paul Manafort on Tuesday approved the prosecution’s request to allow evidence about a Justice Department inspection of Manafort’s lobbying activities in the 1980s but limited the scope of what it can show.

The ruling by Judge Amy Berman Jackson represents a partial win for special counsel Robert Mueller ahead of Manafort’s second trial, which is set to begin next month in Jackson’s federal courtroom in Washington.

Jackson said she wanted to limit the scope of what the government introduces in order to avoid a “trial within a trial” that would involve reviewing reams of evidence.

The prosecution said it would like to introduce evidence to rebut the defense argument that Manafort did not know rules on foreign lobbying. Jackson ordered both sides to agree to a stipulation showing Manafort was notified of lobbying disclosure rules in the 1980s, which would be in place of the government submitting all of its proposed evidence to the jury.

Mueller already scored a victory last week when a jury in Alexandria, Virginia, convicted Manafort on eight counts of bank and tax fraud and failing to declare his foreign bank accounts, a verdict punishable by up to 80 years in prison.

The cases against Manafort resulted from Mueller’s investigation of Russian interference in the 2016 presidential election. Manafort worked for Republican Donald Trump’s successful campaign for several months, including serving as chairman.

Manafort now faces a seven-count indictment in the Washington trial. The charges include allegations of money laundering, obstruction of justice and failing to register as a foreign agent for his lobbying on behalf of pro-Russian politicians from Ukraine.

Mueller’s prosecutors had argued to include evidence at trial that Manafort had been subject in the 1980s to Justice Department inspections related to his lobbying for foreign governments to show that he was aware of the disclosure requirements under the Foreign Agents Registration Act.

The government says the 1980s inspections uncovered 18 instances of lobbying and public relations activities that should have been disclosed, a revelation that prompted Manafort to resign as director of a federal agency in 1986.