On Feb. 15, President Trump declared a national emergency on the U.S.-Mexico border in an effort to obtain money to build a wall. His declaration faces legal and congressional hurdles and has attracted considerable opposition, including from 58 former senior security officials.

Trump is not the first democratically elected ruler to declare a controversial state of emergency. In 1999, Hugo Chávez and the Constitutional Assembly of Venezuela declared a legislative emergency that allowed the constitution to be rewritten, setting the stage for the nation’s descent into authoritarian rule. In 2001, President Gloria Macapagal-Arroyo declared a state of emergency in the Philippines following protests in response to the arrest of former president Joseph Estrada. She did the same thing in 2003, 2006 and 2009.

The extraordinary step of declaring a state of emergency raises fears that leaders will use them to undermine democratic rule. Our research suggests this fear is justified: When leaders declare a state of emergency, their countries are almost 60 percent more likely to experience a decline in democracy. Our research covered virtually all democracies from 1974 to 2016.

This is how we did our research

To measure the health of democracy, we rely on the Varieties of Democracy Institute (V-Dem), which draws on the assessments of more than 3,000 country experts. The V-Dem data shows 54 cases where these experts think a country’s democracy eroded substantially or even broke down during the past 40 years. In some cases, democracies died suddenly, such as after a military coup. However, in most cases, democratically elected rulers gradually undermined constraints and expanded their power.

States of emergency can contribute to these gradual declines in democracy by giving leaders extraordinary powers while allowing them to appear as though they are acting in a democratic fashion. To show this link, we married the V-Dem data to data on declared states of emergency from two sources.

States of emergency coincide with democratic decline

Here’s what we found: States of emergency coincide with democratic decline. Taking into consideration other factors that can affect democracies, such as economic development and inequality, democracies with a state of emergency are 59 percent more likely to decline than without a state of emergency. In most cases, these periods of decline are lethal for democracies: 86 percent of them ended up collapsing after a state of emergency coincided with significant democratic declines.

Why states of emergency can undermine democracy

States of emergency are an ideal tool to undermine democracy because they provide the guise of legitimacy. Because multiparty elections have become the global norm, even dictators invest in appearing democratic and try to avoid sudden moves toward autocracy — such as military coups — that could trigger mass uprisings or international intervention. Dictators would rather manipulate elections and gradually expand their power.

A state of emergency gives rulers not only the opportunity to gain power, but also a good argument for why they need more power. In essence, they can say, “Why should I have to bother with human rights or legislative constraints while the country is under attack?”

Moreover, even if this dictator loses to the opposition, the new leaders have lower incentives to return to the old rules of democracy while they attempt to solidify control of the nation. Thus, states of emergencies can help to dismantle democracy and subvert resistance to its demise.

The case of Turkey is a good illustration. After an unsuccessful coup in 2016, Turkish President Recep Tayyip Erdogan declared a state of emergency in an attempt to “root out the virus” responsible for the coup attempt. Under the Turkish constitution, once an emergency has been declared, the president “may issue decrees having the force of law on matters necessitated by the state of emergency.” Using these emergency powers, Erdogan and his government have jailed more than 40,000 people accused of plotting a coup, fired more than 140,000 people from their jobs, shut down 1,500 civil groups, and virtually eliminated freedom of the press by arresting journalists and closing independent media outlets. International observers no longer consider Turkey democratic.

What this means for the United States

The United States retains a much more robust democracy than Turkey’s. In part this is visible in the resistance to Trump’s declaration of a state of emergency. Nevertheless, our research suggests that Trump’s move raises real risks. It has put the United States into the bad company of eroding democracies and could open the door for further democratic declines.

Anna Lührmann is the deputy director of the V-Dem Institute and assistant professor at the University of Gothenburg in Sweden. From 2002 to 2009, she was a member of the German parliament, the Bundestag.

Bryan Rooney is a junior research fellow at the Carlos III-Juan March Institute in Spain.