A conviction - most likely not - But what you should be concerned with is asking about a warrant for an outstanding charge
Are you planning on lying to Canadian immigration/border inspectors? The inspectors likely will be asking about your convictions.
Canada has consulates throughout the US. Here's the link to the consulate in Seattle: http://geo.international.gc.ca/can-am//seattle/menu-en.asp . From there you can choose the site closest to where you live.
Here's what on the consulate's webpage regarding convictions: "Members of Inadmissible Classes include those who have been convicted of MINOR OFFENCES (including shoplifting, theft, assault, dangerous driving, unauthorized possession of a firearm, possession of illegal substances, etc.), or of INDICTABLE CRIMINAL OFFENCES (including assault with a deadly weapon, manslaughter, etc.). As well, those who have been convicted of DRIVING WHILE INTOXICATED (DWI) are considered Members of an Inadmissible Class. Driving while under the influence of alcohol is regarded as an extremely serious offence in Canada."
Canada provides a way to seek a waiver: "Those who have been convicted of an offence OUTSIDE CANADA, and have had 5 years elapse since the termination of the custodial portion (if any) of the sentence imposed (not the sentence served), may apply for a Minister's APPROVAL OF REHABILITATION. The Minister's Approval will permanently remove the inadmissibility caused by conviction."
The procedures are in the consulate's webpage.
Canada is extremely strict with respect to admitting people with a DUI conviction or any criminal records. Surprisingly for Americans, they consider DUI to be a serious crime which will prevent you from entering. If you have a DUI conviction, then you are a member of an "inadmissible class." In fact, when President Bush took office, there was some question whether he could travel to Canada because of his old DUI conviction.
The Canadian Consulate has set up a web site to tell you how to get "rehabilitated" if you have a DUI conviction.
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