Earlier this month, Japan and the United States began sharing fingerprint data among their law enforcement agencies under a bilateral agreement.

The little-known agreement, negotiated in 2014 by the administrations of Prime Minister Shinzo Abe and then-U.S. President Barack Obama, is intended to strengthen cooperation on fighting terrorism and organized crime by allowing their national databases to be cross-referenced.

While the agreement allows Japan’s National Policy Agency and American law enforcement agencies like the FBI and the Department of Homeland Security to work more closely together, human rights advocates fear the data might be abused.

Here are the key points behind the issue:

What is the agreement’s main purpose?

The agreement is intended to prevent and fight serious crimes and terrorism in both countries. It is also aimed at securing international travel by allowing both to identify whether arriving individuals have been fingerprinted over “serious crimes.”

What constitutes a “serious crime?”

The agreement defines the term as “an offense punishable by death, life imprisonment or deprivation of liberty for a maximum period of more than one year.”

The agreement’s annex lists 34 different crimes that fall under its scope. These include terrorism, murder and manslaughter, rape, assault and white-collar crime like racketeering, bribery or corruption, embezzlement, cyberattacks, data theft and intellectual property offenses.

Child pornography and trafficking or possession of illegal narcotics and firearms are also included.

Trafficking in or smuggling of people is also listed as a serious crime.

How does the agreement work?

The NPA, FBI or DHS can request the fingerprint data of an individual for prevention, detection and investigation of serious crimes only if there is just cause to inquire whether the person will commit, or has committed, a serious crime.

An automated fingerprint identification system will be installed in both countries, and the queried party’s database will automatically respond if there is a match.

What happens if there’s a match?

If there’s a match, the confirmation response will be followed by fingerprint data to allow the other party to confirm it. The inquiring party can also receive the name of the person whose fingerprints match along with other information, including arrest and conviction records.

If there’s a match but the country that made the query doesn’t follow up with a request for further information, the other country can request an explanation as to why the initial query was made.

How many fingerprints are currently in the databases in both countries?

The NPA says the FBI has fingerprints from about 75 million people and the DHS has the prints of nearly 230 million people.

Japanese authorities have the fingerprints of nearly 11 million people who have been taken into custody. There are nearly another 380,000 latent fingerprints taken in cases that remain unsolved.

What are the concerns about the deal?

In April 2014, after the U.S. and Japan signed the agreement but before the Diet ratified it, the Japan Federation of Bar Associations raised several concerns in a statement.

The group questioned the need to forge a new agreement, citing the existence of similar accords between Tokyo and Washington.

One is a 2002 agreement on legal assistance in criminal matters; the other is a 2004 revision to a law designed to expedite bilateral cooperation on fingerprinting information.

The governments of the U.S. and Japan say the purpose of the new agreement that took effect this month is logistical, in other words, to reduce the waiting periods that follow after an inquiry by one party or the other is made.

The Japanese bar association also complained that the scope of offenses defined as “serious crimes” is too broad, and that allowing such sensitive data to be shared could lead to fingerprints being used to achieve objectives different from the agreement’s intended purpose.

Should we be worried?

According to the bar association, there was only one case in which American authorities asked Japan for fingerprint information between 2010 and 2012.

However, concerns about privacy remain. This could be caused by administrative mistakes — including scenarios where the prints of someone acquitted of a serious crime aren’t removed from the two databases.