Under federal immigration law, the victim of a serious crime may be eligible to apply for a what's known as a "U visa" in order to help law-enforcement officials with its investigation and possibly prosecution. (After all, it wouldn't do U.S. law enforcement much good if a key witness had to leave the U.S. due to expiring or nonexistent immigration status.)
Approval of a U visa allows the non-citizen temporary and perhaps permanent legal status in the United States. The application process involves submitting Form I-918, Petition for U Nonimmigrant Status, to U.S. Citizenship and Immigration Services (USCIS), along with a “certification of helpfulness” (I-918 Supplement B, U Nonimmigrant Status Certification).
The latter has been difficult for some immigrants to obtain, however. It involves persuading a law enforcement official (judge, police officer, prosecutor or other) to “vouch” for the non-citizen's petition, certifying that the person has been a victim of qualifying criminal activity, has information that will be useful to law enforcement, and is cooperating in order to bring the perpetrator to justice.
But many law enforcement officials do not understand the law, or do not wish to assist an immigrant, or take a narrow view of what is "helpful," and therefore refuse or ignore the requests to complete the certification.
To deal with this issue, the California legislature passed, in 2015, SB 674. This new law mandates that law enforcement officials sign the I-918 Supplement B under certain conditions. Importantly, it establishes a rebuttable presumption that a victim is helpful, has been helpful, or is likely to be helpful to the detection, investigation, or prosecution of that qualifying criminal activity, if the victim has not refused or failed to provide information and assistance reasonably requested by law enforcement.
Law enforcement agencies must report to the state on how many requests they received and how many they denied. This should pressure agencies to not take a blanket approach to denials but to pause and consider which cases actually merit signing the I-918 Supplement B.
If you are the victim of criminal activity in the U.S. and do not have legal status, look further into the possibility of a U visa or consult an attorney.