Special Notice / Hearing: None__
Vote Required: Majority
To: Honorable Board of Supervisors
From: Ken Binder, Sheriff’s Office
Subject: Sheriff’s Office report on Immigration Activities
RECOMMENDATION:
title
Accept the Sheriff’s Office Report on Immigration Detainers, pursuant to Chapter 2.48 of Title 2 of the San Mateo County Ordinance Code.
body
BACKGROUND:
On November 14, 2025, the San Mateo County Board of Supervisors adopted an ordinance amending Chapter 2.48 of Title 2 of the San Mateo County Ordinance Code that requires the Sheriff’s Office to provide a written report on immigration activities, including civil immigration detainer requests as well as any communications related to immigration authorities by March 1st, June 1st, September 1st, and December 1st of each year.
DISCUSSION:
The Sheriff’s Office is committed to maintaining public safety and public trust and ensuring transparency within San Mateo County, particularly among immigrant communities.
Definitions:
1. Immigration Detainer is a request from U.S. Immigration and Customs Enforcement (ICE) to a local jail or police department.
What it is:
A notice saying: “If you’re about to release this person, please hold them for up to 48 extra hours so ICE can come pick them up.”
Important:
• It is not a judge’s order.
• It’s an administrative request from a federal immigration agency.
What it means to act on it:
If a jail “acts on” a detainer, they keep the person in custody for up to 48 additional hours after they would otherwise be released, so ICE can take custody.
2. Judicial Warrant is an official order signed by a judge.
What it is:
A judge reviews evidence and formally orders law enforcement to do something specific such as:
• Arrest someone
• Take someone into custody
3. Judicial Booking is taking custody of the person arrested.
The table below represents the number of communications the Sheriff’s Office has received from immigration authorities since January 2025.
|
Date |
Year |
Immigration Detainers Received |
Number of Detainers Acted Upon |
Judicial Warrants or Judicial Bookings Received** |
|
|
|
|
|
|
|
January |
2025 |
* |
0 |
0 |
|
February |
2025 |
* |
0 |
0 |
|
March |
2025 |
70 |
0 |
0 |
|
April |
2025 |
82 |
0 |
0 |
|
May |
2025 |
107 |
0 |
0 |
|
June |
2025 |
112 |
0 |
1 |
|
July |
2025 |
132 |
0 |
0 |
|
August |
2025 |
91 |
0 |
0 |
|
September |
2025 |
112 |
0 |
0 |
|
October |
2025 |
106 |
0 |
0 |
|
November |
2025 |
67 |
0 |
0 |
|
December |
2025 |
91 |
0 |
0 |
|
January |
2026 |
70 |
0 |
0 |
|
February |
2026 |
56 |
0 |
1 |
|
March |
2026 |
89 |
0 |
0 |
|
April |
2026 |
102 |
0 |
1 |
|
May |
2026 |
117 |
0 |
1 |
|
Totals |
|
1404 |
0 |
4 |
* Information was not collected prior to March 2025
In February 2026, the Sheriff’s Office was notified that an individual in custody at another law enforcement agency within California was available for transfer pursuant to an arrest warrant issued for a crime committed in San Mateo County. Upon taking custody of the individual and completing the booking and warrant verification process, it was determined that an additional federal judicial warrant had been issued for the individual’s arrest. Following resolution of the San Mateo County matter with credit for time served, the individual was released to the custody of the Department of Homeland Security (DHS) on May 5, 2026.
In April 2026, the Sheriff’s Office received a federal judicial warrant for the arrest of an individual who has already been in custody since March 2026 in connection with crimes committed in San Mateo County. Following the resolution of the San Mateo County matter with credit for time served, the individual was released to the custody of the Department of Homeland Security (DHS) on April 20, 2026.
In May 2026, the Sheriff’s Office received a federal judicial warrant for the arrest of an individual who had already been in custody since April 2026 in connection with a crime committed in San Mateo County. Following resolution of the San Mateo County matter with credit for time served, the individual was released to the custody of the Department of Homeland Security (DHS) on May 26, 2026.
COMMUNITY IMPACT:
The Sheriff’s Office serves adults impacted by the justice system, including immigrants, minorities, youth of color, low-income families.
Through this report, the Sheriff’s Office strengthens its commitment to serving its clients regardless of their immigration status.
FISCAL IMPACT:
There is no fiscal impact related to this report.