Originally Posted by cyccommute

Technically this is incorrect. The laws state that an uncontrolled intersection should be treated like a 4-way stop or inoperable stoplight. In other words, you should yield to the car to your right. If they arrive at the same time, vehicle A has the right of way as it is the vehicle to the right.

Unfortunately this is not the way that that most people think and anyone in vehicle A would be foolish to try and assert their right of way.