The fine for an obstructed plate is $115. Not sure what the exact rule is but like most it will be up to interpretation. Your plate must be clearly visible from both directly behind and from an angle (think photo radar's view) you must also light the plate. I you relocate your plate you may also need to relocate the light. Many bikes use the tail light as the plate light if this is the case for your bike you may need to add an additional light for the plate.

I found this information on another forum,  or click on the link and it gives direct links to the PDFs it refers to...
http://www.kawasakimotorcycle.org/forum/kawasaki-cruisers/123487-alberta-vertical-plate.html

"I got the story from Alberta Government on vertical plate mounting:

Thank you for visiting the Alberta Government feedback web site. Following is the response to your question prepared by Transportation :

Thank you for your provincial government web inquiry of February 2, 2010 regarding motorcycle licence plate location and lighting.

Alberta's Operator Licensing and Vehicle Control Regulation doesn't specifically allow or prohibit a vertically mounted motorcycle licence plate. However, a peace officer may not consider a vertically mounted licence plate to be legible, meaning easily read.

The vehicle owner is required to have the licence plate securely mounted to the rear of the vehicle, legible and clearly visible at all times. Alberta's Operator Licensing and Vehicle Control Regulation section 70, requires the licence plate of a motorcycle to be on the rear mudguard or rear fender so that it is clearly visible. Section 71 requires the plate to be legible and clearly visible at all times. You may wish to review sections 70 and 71 of the Operator Licensing and Vehicle Control Regulation on the Queen's Printer's website:

Alberta Queen's Printer: Legislation PDF

Licence plate lamps are mandatory in Alberta. The Vehicle Equipment Regulation section 14 requires a licence plate to be illuminated by the tail lamp or a separate licence plate lamp so the plate is clearly visible from at least 15 metres to the rear. A separate licence plate lamp may emit white light. You can view the Vehicle Equipment Regulation at this web link:

Alberta Queen's Printer: Legislation PDF

For further information please contact Howard Greenway, Vehicle Standards Specialist, 780-427-7573 or, email: Howard.Greenway@gov.ab.ca

Thank you for using the government website. "

Good post, thanks for the info.

This spring I mounted my plate vertically off of my left swingarm.  The plate is lit, but according to Section 70, I might get in trouble if/when I get stopped.  In addition, I had to trim my plate a bit, which I'm sure isn't exactly legal either. 

On at least 2 occasions, I've had a cop car directly behind me when stopped at a light and so far they've either didn't notice or let it slide.  I figure if I don't give them a reason to stop me (i.e. excessive speeding, stunting, etc) they won't hassle me - hopefully that theory holds...