Will Canadian citizens be affected by US law requiring machine readable passports?

Not directly. Beginning on September 30, 2004, US-bound travelers from many of the 27 Visa Waiver Program (VWP) countries will become subject to the US-VISIT biometric screening system, which requires many non-US persons to be photographed and to provide inkless fingerprints on admission. A separate US law, however, provides that Canadian citizens do not require visas to travel as business visitors, tourists, or students (among other classifications) so that Canada is not a VWP participating country. As such, Canadian citizens will not be subject to US VISIT processing. They may be affected by delays caused by the additional processing burden placed on other travelers, however.