Part of an occasional series looking at language dominating the news and influencing how Americans learn about the way our government works.

The media are filled with speculation about whether each twist and turn of the Russia-Trump investigation will “prove collusion.” A recent Vanity Fair headline read “Does Trump’s Tangled Russia Web Constitute Collusion?” and a Vox headline asserted that “Trump administration: There’s no evidence of collusion.”

What is collusion? Is collusion a crime?

The dictionary definition of “collusion” is a “secret agreement or cooperation, especially for an illegal or deceitful purpose.” But when it comes to the unfolding story of possible ties between the Trump campaign and Russia, the word is being used as a catch-all term for illegal acts such as conspiracy, espionage, campaign finance violations, bribery, or fraud. There is no federal law making collusion a crime.

While “collusion” has proven to be a useful word for journalists and the general public, it also serves as a useful straw man for defenders of President Trump; they argue that collusion is not a crime and that the Trump campaign’s activities did not constitute collusion, so there’s no reason for further investigation.

However, the fact that there’s no law prohibiting “collusion” doesn’t mean there’s no statute prohibiting some of the specific activities that the Trump campaign engaged in, or may have engaged in.

For example, federal law bars the solicitation or receipt of a contribution from a foreign national. Last week, Common Cause filed complaints with the Federal Election Commission and Department of Justice alleging that the Trump campaign violated this prohibition when Donald Trump Jr. asked for a meeting with a Russian to receive what he believed would be valuable opposition research on Hillary Clinton.

Federal law also prohibits candidates from cooperating or consulting with a foreign national who is spending money to influence a U.S. election. These “coordinated expenditures” are treated as contributions under campaign finance law and thus run afoul of the law’s ban on contributions from foreign nationals in U.S. elections.

Finally, federal law prohibits two or more persons from conspiring to commit a crime—an offense known as “criminal conspiracy.”

As evidence of Trump campaign interactions with Russian nationals connected to Putin’s government continues to mount, investigation by the Department of Justice, the Federal Election Commission and Congressional Committees is necessary. And though “collusion” is a convenient word for describing these potential violations, our justice system rightly demands precision when it comes to defining violations of the law. In the coming weeks and months, we’ll explain the legal meaning of important terms like “coordination” and “conspiracy.” So stay tuned!