John Paul Stevens, who served on the Supreme Court for 35 years until his retirement in 2010, died this Tuesday. Just before Stevens stepped down from the bench, he authored one of the most significant opinions of his career: the main dissent in the infamous case Citizens United v. Federal Election Commission.

“Justice Stevens clearly saw what most people know, that corporations are not people and they should not have the same political rights,” says Ellen Weintraub, chair of the Federal Election Commission.

Nine years later, we know that one specific aspect of Stevens’s warning was completely right: Citizens United did indeed make it possible for foreign money to enter the U.S. electoral system via corporations.

“If taken seriously,” Stevens wrote in his opinion, “our colleagues’ assumption that the identity of a speaker has no relevance to the Government’s ability to regulate political speech would lead to some remarkable conclusions. … It would appear to afford the same protection to multinational corporations controlled by foreigners as to individual Americans.”

U.S. law strictly forbids any “foreign national” from spending money in U.S. elections. A foreign national is defined as a foreign individual, a foreign corporation, or a foreign government.

Yet during the 2012 election, the notorious Malaysian financier Jho Low appears to have funneled over $1 million via an American LLC to a super PAC that supported Barack Obama’s candidacy.

During the 2016 election, an investigation by The Intercept discovered, a California corporation wholly owned by Chinese citizens gave $1.3 million to a super PAC supporting Jeb Bush’s presidential candidacy.

In 2017, a $100,000 donation to the Trump Victory committee — a joint fundraising committee for the 2020 Donald Trump campaign, the Republican National Committee, and several state GOP parties — may also have originated with Jho Low, with an intermediate stop at an American corporation.

And in 2018, an Illinois corporation largely controlled by a Canadian billionaire gave $1.75 million to a super PAC that supports Trump’s agenda.

How can this be? It’s all thanks to Citizens United.

Before Citizens United, contributions to candidates for federal office could only come from individual U.S. citizens in limited amounts. After Citizens United and related decisions, corporations could contribute unlimited amounts to super PACs that supported federal candidates, as long as the super PACs weren’t formally coordinating with their campaign.

Citizens United did not change the prohibition on foreign nationals putting money into American elections. But the decision created a huge loophole — because as long as a company is incorporated in the United States, it is legally a U.S. national, even if it is wholly owned by foreigners.