reply to elwoodblues
Re: [Rant] Ontario Photo ID card now available at more locations Police can detain you for the purpose of obtaining your identity if they suspect a crime has been committed and have reasonable grounds to believe you may have participated.
They can also detain you while they investigate if they have reasonable grounds to believe that you have direct knowledge of the crime.
Also, they can demand your ID for the purpose of issuing a ticket. For instance, if you jaywalk they can certainly ask you for ID.