[emmalee]

Are there certain crimes that would prevent a person entering USA?

For instance child sex offences?

[Clough]

The question that you ask raises issue that are very complex. I don't that any one person here could have the perfect answer for you. However, I did find on the following site a list of things including crimes that could make a person ineligible for entry into the United States. The quote below is from that site. I would think the bottom line concerning entry would be the possible level of threat that the person who has committed a crime might pose to the United States. The information on that site is worth checking out.

Form I-192, Application for Advance Permission to Enter as a Non-Immigrant and Inadmissible Canadian Information - CBP.gov

(06/09/2008)

There are many reasons a person may be ineligible to enter the United States. The legal descriptions are lengthy and complex, so to help you understand them, we are providing a general description of the most common ones. This list should not be taken as a complete list of reasons to be excluded from entry. (Legal Descriptions) In general, you might be denied entry:

If you have a communicable disease,

If you have a criminal record for crimes of moral turpitude,

For possession of or trafficking in a controlled substance,

If you have any involvement with terrorism or terrorist organizations (no waivers can be approved for this category),

If you have trafficked in persons,

If you have been involved in money laundering,

If you might become a public charge because of limited financial resources,

If you have been previously removed (deported) or have overstayed a previous period of admission to the United States

Just because a person might be listed as a sex offender in another country might not be a reason to deny them entry into the United States. I would think that there would be many factors to be considered in that instance. For example, the severity of the offense, the length of time since committing the offense, the type of punishment that has already been received, any type of counseling/treatment that has already been completed successfully, what manner and type of retribution to society the person has made since committing the offense and the personal written and verified testimonies of those who have known the offender for a considerable length of time.

[Clough]

I just found a pretty exhaustive list available on the following site that is run by the U.S. Department of State. However, it is too large to be included in this thread in order to keep within the rules of what is okay to copy and paste here.

Classes of Aliens Ineligible to Receive Visas

[lawanwadee]

Clough is correct...

Green card holders can also deported if found committing crimes. Many get away until they apply for naturalization. Any crimes that are considered crimes of moral turpitude can lead to deportation, including some DUI cases.