The White House is looking at whether it can use a federal ethics rule to limit the scope of the special counsel investigation into Russian interference in the 2016 election and alleged ties between members of President Donald Trump’s campaign and Russia, Reuters reported on Friday.

Trump’s administration began reviewing the Code of Federal Regulations on Wednesday shortly after the Justice Department announced its hiring of a special counsel, according to Reuters’ report, which cited two unnamed sources “familiar with White House thinking.”

That code previously prohibited executive branch appointees from involvement in matters regarding their former employers or clients for one year after their appointment. Trump signed an executive order in January extending that time period to two years.

Former FBI Director Robert Mueller, who the Justice Department named as special counsel in the probe, resigned his position at law firm WilmerHale to lead the investigation. Clients of the firm include Ivanka Trump, Jared Kushner and Trump’s former campaign chairman Paul Manafort, Politico reported on Wednesday.

Reuters reported that without a waiver from the Justice Department, Mueller would be barred by the rule from investigating those members of Trump’s administration.

Even if Mueller is granted a waiver, those sources told Reuters, the White House may use the rule as part of a press strategy to “create doubt about Mueller’s ability to do his job fairly.”

And if Mueller’s findings lead to a prosecution, Reuters reported, the White House may use the rule as part of its legal strategy.