Border patrol agents in the Texas Rio Grande Valley sector used their own discretion to release about 150 migrants Saturday evening without giving them a court date, Axios has learned.

Why it matters: The use of prosecutorial discretion by border patrol to release migrants without a notice to appear in court is unprecedented, according to multiple sources, and is yet another sign of how overwhelmed parts of the border are becoming.

• The Rio Grande Valley sector had roughly 5,100 migrants in custody as of Sunday, Rep. Henry Cuellar (D-Texas) told Axios.
• They were supposed to keep the number of migrants in their custody to about 700 because of the COVID-19 pandemic.

The latest: Guidance sent to border patrol in the sector on Saturday from agency leadership told border patrol agents they can decide to release some migrants — often at bus stations or nongovernmental organizations — without a notice to appear in court, according to a source familiar with the correspondence.

• Migrant families and adults are usually first referred to Immigration and Customs Enforcement (ICE) to determine if and where migrants will be detained.
• Agents are still using an emergency public health order to quickly expel migrant adults and some families, but the guidance gives them more leeway in deciding what to do on a case-by-case basis, according to the source.
• The guidance also says COVID-19 testing should be administered whenever possible. The government has largely relied on local agencies and nongovernmental organizations to provide testing for migrant families and adults.
• Fox News first reported on the move, citing multiple border patrol agents.

What they're saying: "In some cases, families are placed in removal proceedings further along in the release process rather than while they are at the border patrol station," a DHS official told Axios in a statement.

• "All families, however, are screened at the border patrol station, including the collection of biographical and biometric information and criminal and national security records checks."

Go deeper: Nearly 1,000 kids held by border patrol for more than 10 days