running to first

Question
A batter has hit the ball and is running to first. The ball is thrown to the first baseman who is standing on half the bag so the runner slows down? Should the firstbase man be called for interference? Should the runner be out?

Answer
I am no expert on the rules...perhaps you should see if there are umpires to answer this question with authority.  However, I will tell you what I believe: the runner always has a right to his baseline.  A fielder always has a right to move to the ball or to the base to make a play.  If the first baseman was blocking the runner before he was even involved in catching the ball, then, yes, I would say that could be called interference.  More than this, a first baseman who touches any part of the bag besides a corner is risking his own safety.  That is not to say that the runner can intentionally crash into him, but that might happen, even if the runner is trying to avoid a collision.  I don't think there would be any interference call as long as a runner is trying to run across the base, and as long as the fielder is trying to step on that base.  The proper way first basemen are taught to tag the base is to step on the infield side of it and run up toward right field, alongside the runner, and not crossing the foul line (NOT across the base toward the dugout or coaches box.)  Again, there could be umpire judgement involved here.  An ump might call interference on the runner if he thinks he intentionally tried to collide with the fielder.  I don't think a first baseman could be called for interference if he was going after the ball, or if he was going to the base.  Hope this "unofficial" answer helps.