Violent crimes will automatically and immediately cause a rejection, such as murder, kidnapping, or sexual violence. Non-violent crimes can also result in rejections. However, pardons can be applied for in some instances, like in the case of illegal entry into the country by the spouse of a US citizen. Timing also becomes a reason for rejection if someone of Special Immigrant Juvenile Status applies before a green card is available, or if someone here on a Visa does not follow the policies and procedures necessary to stay here legally. As you can see, the green card application process is tricky and each case is unique.