In almost every situation in which people apply for a U.S. immigration benefit, the government will consider their moral character.
In some cases, applicants are required to show "good moral character" as an explicit part of the application. For example, for naturalized U.S. citizenship or cancellation of removal for non-lawful permanent residents, applicants must show that they have had "good moral character" for a certain period of time as specified by federal statute.
The immigration statute provides a specific definition for "good moral character" at Immigration and Nationality Act Section 101(f), 8 U.S.C. 1101(f). Under the statute, if you commit certain acts or hold a certain status within the statutory period, you may be found to automatically lack good moral character regardless of the underlying circumstances of the event, including:
In addition, under the definition for "good moral character," the U.S. government may consider other acts that fall outside of the specific statutory period in assessing your good moral character, and it may determine that these show that you lack good moral character.
In some cases, you might not be specifically required to show good moral character, but it is still effectively considered before approving your application. For example, it might be considered indirectly, or it might be taken into account in an officer's legal discretion.
Applications for an immigrant or nonimmigrant (temporary) visa, for instance, do not specifically require that you show good moral character. But they do require that you have not committed certain acts, like certain crimes, fraud, or immigration violations. These grounds of inadmissibility are thus tied to your good moral character.
In addition, when considering visa applications, the U.S. government may deny admission as a discretionary matter, even if you are not technically inadmissible. For example, driving under the influence (DUI) offenses generally do not make applicants automatically ineligible for immigration benefits. However, immigration authorities still take DUI offenses very seriously and may use a record of DUI offenses (especially recent or multiple offenses) to deny benefits in the exercise of discretion. Also, a history of questionable moral acts might make the officer wonder whether you will comply with the basic terms of the visa you're applying for, as opposed to flouting the law and, say, failing to leave the U.S. when you're supposed to.
If you are denied an immigration benefit as a matter of discretion, it is usually difficult to appeal it.
It is therefore important, before you apply for a visa, green card, or other immigration benefit, to know whether the benefit has an explicit or implicit good moral character requirement and what acts might disqualify you from the benefit.
Also be prepared to address any negative issues in your case, even if they do not automatically bar you from the eligibility for the benefit. It is better to present a strong application affirmatively than try to reverse a negative decision against you.