The United States government has an extensive list of crimes, which it classifies as crimes of moral turpitude, that could exclude a Canadian from entering the country. The most common among these crimes are murder, rape, manslaughter, forgery, bribery, theft, prostitution, fraud and aggravated battery.
However, there are a host of crimes that are not classified as "moral turpitude," those include driving under the influence, disorderly conduct, breaking and entering and simple assault. Nevertheless, if someone has been convicted of a number of these crimes, it could still result in a denial of entry into the United States.
Some individuals may be able to seek a waiver of their denied entry. The process of applying for a waiver can take a long time -- as much as a year -- and it is also costly: $585 U.S. dollars for each application. If the application results in denial, no refund is allowed. Checks for the fee need to be certified checks issued by a U.S. bank and they are made out to U.S. Customs and Border Protections.
In most situations, Canadians do not have a difficult time when entering the United States for tourist reasons. However, a criminal record as described above could present difficulties. In these cases, visa applicants may wish to speak with an immigration lawyer who is familiar with U.S. law. The purpose of the visa applicant's visit will also dictate the appropriate strategy. For example, is this a work visa or a short term tourist visa? All this and more can be answered with an appropriate strategy by a Canadian immigration lawyer.
Source: U.S. Customs and Border Protection, "Entry into the U.S. - Canadian with criminal record or overstay, waiver," accessed July 06, 2016