The Iran-Contra affair or "Irangate", was a secret arms deal where the U.S. government traded weapons like missiles and guns to Lebanese terrorists. These terrorists held American hostages and the U.S. would sell them arms to free them. However, these funds used for the secret deal would also be used to support an anti-Communist rebel group in Nicaragua, known as the Contra's.
In 1980, President Ronald Reagan won the White House and promised his supporters during his campaign that he would assist any and all anti-Communist insurgencies around the world, which was known as the Reagan Doctrine. Unfortunately for President Reagan, the Republican Party lost the majority in both the Senate and the House of Representatives during the mid-term elections in 1982. When the Democrats took over Congress, they would pass the Boland Amendment, which restricted the CIA and Department of Defense to involve itself in foreign conflicts. The Boland Amendment actually specifically targeted the conflict in Nicaragua during that time, as the Sandanista government was fighting the Contras, an anti-Communist rebel group that earned the majority of their funds through the drug trade. Despite this new law, President Reagan ordered his National Security Advisor, Robert MacFarlane, to discover a way to help the Contras regardless of the consequences.
Around the time President Reagan started secretly assisting the Contras, Reagan was also dealing with a dire situation in the Middle East. Sometime during 1985, Iran-backed terrorists in Lebanon had taken several American hostages and President Reagan would respond by negotiating with Iran. Robert MacFarlane told Reagan that Iran was interested in buying weapons from the US to help them fight against Iraq, even though there was currently a U.S. trade embargo on Iran. Despite that, President Reagan would agree to an arms deal and take some of the funds earned from it to arm the Contras in the process as well.
The public would not learn of this arms deal until 1986, where a Lebanese newspaper called, Al-Shiraa, reported about the secret arms deal between the U.S. and Iran. The press in America would report about this scandal for the rest of Ronald Reagan's presidency. In the end, around 14 people, including MacFarlane, were charged and served time in prison. Despite being one of the biggest political scandals in the 20th century, this scandal is often overlooked and unlike the other scandals, Ronald Reagan would be forgiven by most of the public.
This is just one of the few examples of the Watchdog Rule being used by the American press to enlighten citizens and hopefully prevent any further abuse of power from the branches of government. Citizens have a role in the checks-and-balances system, and it is to ensure that our government doesn't cross the line.
Source: https://www.history.com/topics/1980s/iran-contra-affair