I was told that there was a law passed preventing convicted felons from marrying immigrants. It that true? I also heard that John Walsh was some way involved in the law being passed.

I haven't heard anything about this law it would be difficult to pass as this is a restriction on a marriage of a US citizen. Most of the restrictions are going to be state based--age, level of consanguinity, mental condition, etc.

But please note, I am not an expert and maybe the family law would be a good place to check.

Not sure about illegals in US, but in the past year US consulates in Asia denied many cases at the interview. In most cases, petitioners had records such as domestic violence, registered sex offender, child pornography, and related.