In the decades before President Donald Trump asked Ukraine to launch an investigation into his main political rival in the upcoming presidential election, Congress tried again and again to keep foreign nationals out of American elections and government decisions.

The lawmakers’ adversaries over the years sound as if they come straight out of Hollywood scripts: the Nazi party in the 1930s, the Philippine sugar industry in the 1960s, a Greek industrialist in the 1970s, an international businessman turned Chinese government agent in the 1990s.

Congress passed laws to ban what they saw as threats to the integrity of elections, foreign policy and national security. Foreign nationals found loopholes or new ways to contribute to campaigns.

Now, the person testing the legal limits of the current ban isn’t a foreign national, but the president of the United States and his political team. And House Democrats, although they have put Trump’s actions at the heart of their impeachment inquiry, don’t have plans to more explicitly outlaw politicians from requesting election-related information from foreign nationals.

Democrats already had various bills to bolster the 2002 campaign finance law, based on Russian interference in the 2016 presidential election, when a whistleblower reported concerns that Trump in July had pressured Ukraine to start an investigation into Democratic presidential candidate Joe Biden.

Trump’s call was so unusual that intelligence community officials alerted the Justice Department of a possible violation of that law, which makes it a crime for foreign nationals to give contributions or any other “thing of value” in connection with an American election — and a crime to solicit such contributions.

The Justice Department determined that Trump did not cross a legal line, reigniting a broader unsettled debate about whether political dirt or opposition research would qualify as a “thing of value.”

Similar issues arose from former special counsel Robert S. Mueller III’s investigation into Donald Trump Jr. and other Trump campaign officials taking a meeting at Trump Tower about possible dirt on Hillary Clinton that the Russians might have obtained.

Democrats say they don’t plan to add language to clarify what counts as a “thing of value” under the ban, even as the House Administration Committee on Wednesday advanced a broad bill that seeks to close loopholes in the law that the 2016 election exposed.

Chairwoman Zoe Lofgren, when she introduced the bill earlier in October, said that “the Trump campaign and White House have welcomed and repeatedly solicited foreign assistance for his political activities.”

Among other provisions, the bill would make it a crime for candidates or their campaigns to give a foreign national nonpublic information related to an American election, a response to allegations that Trump’s former campaign manager, Paul Manafort, gave data to a person associated with Russian intelligence.

But Lofgren, a California Democrat, told CQ Roll Call on Wednesday that she wouldn’t add a provision to clarify a “thing of value” because opposition research, even just a tip from a foreign national, already counts.

“I don’t think there is a need to,” Lofgren said. “I don’t think in statutory language you’re going to list everything that could be a thing of value. Clearly that is a thing of value; people pay for it.”

Rep. Jamie Raskin, a Maryland Democrat and a committee member, former constitutional law professor and outspoken critic of Trump’s actions, said Wednesday he would “resist the implication that this is something that we need to explicitly identify now because it wasn’t clear. I think it was always clear.”

But off the Hill, a “thing of value” is not well defined and has not been fully tested in court, leaving sharp disagreement among legal experts about whether Congress could even ban a candidate from asking a foreign government without stepping on the First Amendment.

Bob Bauer, a former White House counsel during the Obama administration, said at a panel this month that the Ukraine and Trump Tower episodes show “a particular degree of lawlessness” when it comes to enforcement of the 2002 law, which has been strongly backed by the federal courts.

“It’s getting softened now in a serious way,” Bauer said. “I’m very disturbed, obviously, by any senior elected official or senior official who appears to be taking actions that suggest a very aggressive view of how much space there is to invite foreign nationals into the electoral process.”

House Intelligence Chairman Adam B. Schiff of California, who now is leading the House Democrats’ impeachment inquiry, introduced a bill in June to address the issue directly. The bill would simply change “thing of value” in the law to “thing of value (including information sought or obtained for political advantage).”

“For the last two years, the country has been gripped by an investigation into Russian interference in the 2016 election, yet the president still thinks that it’s OK to accept campaign assistance from a foreign power,” Schiff said at the time.

That was before the Ukraine call. The bill has stalled at the House Administration Committee. Schiff’s office did not return a request for an update on the bill’s status.

The federal courts left no doubt in 2012, the last time the current law was challenged, that Congress has a compelling interest to minimize the participation of foreign citizens in American elections, and that such sentiment goes back to the nation’s founding.

The framers had an “obsession with foreign influence” that “derived from a fear that foreign powers and individuals had no basic investment in the well-being of the country,” the federal appeals court in Washington decided.

That opinion was written by then-Judge Brett M. Kavanaugh, and was summarily affirmed 9-0 by the Supreme Court on which he now sits. In that case, Bluman v. Federal Election Commission, courts upheld the ban on contributions from foreign nationals lawfully residing inside the United States.

The story of how Congress passed that ban, currently in the thick of the debate about whether to impeach Trump, stretches back to the 1930s, when Congress found that the Nazi party of Germany and other foreign organizations had paid for propaganda disseminated in the United States by foreign nationals.

In the early 1960s, Congress found the Philippine sugar industry, interested in the government’s allocation of federal sugar import quotas, contributed to the campaigns of 20 members of Congress.

During Watergate, investigators probed contributions to President Richard Nixon’s campaign from citizens of foreign countries, including a Greek industrialist soon after his firm was awarded a contract to supply fuel for the U.S. Sixth Fleet.

Then, after the 1996 presidential election cycle, the Senate Committee on Governmental Affairs investigated how campaigns had been financed and found that foreign nationals—some believed to have acted on behalf of foreign governments—had exploited a so-called soft money loophole to purchase access to powerful American officials.

It’s unclear how courts would rule if the law sought explicitly to ban a candidate or campaign that asked a foreign government for information.

Mueller discussed the issue in his report on Russian interference in the 2016 presidential election, to explain his decision not to charge Trump Jr. or other Trump campaign officials over the Trump Tower meeting on Clinton.

In the report, Mueller said that “candidate-related opposition research given to a campaign for the purpose of influencing an election could constitute a contribution to which the foreign-source ban could apply.”

But Mueller discussed the “voluntary provision of uncompensated opposition research” and First Amendment concerns, and wrote, “It is uncertain how courts would resolve those issues.”

And the Justice Department decided Trump did not cross a legal line in the July call with Ukrainian President Volodymyr Zelenskiy, and did not find a “thing of value” that could be quantified as campaign finance law requires.

House Democrats criticized that DOJ decision. And FEC Chairwoman Ellen Weintraub posted a memo on Twitter on Sept. 26 that stated the commission has recognized the “broad scope” of the ban and found that contributions can be banned even where the value may be nominal or difficult to ascertain.

In 2017, legal experts lined up on both sides of whether trying to get that information from foreign governments was prosecutable even if counted as a “thing of value” for a campaign.

Such a crime could result in candidates being barred from asking questions of foreigners, just because the answers might be especially important to voters, Eugene Volokh, a professor at UCLA School of Law, wrote in The Washington Post at the time.

“And it seems to me that restrictions on providing information to the campaigns — or on campaigns seeking such information — can’t be constitutional,” Volokh wrote. “Can it really be that the Clinton campaign could be legally required to just ignore credible allegations of misconduct by Trump, just because those allegations were levied by foreigners?”

Without more action from Congress, such questions could remain unanswered.