Serious Question

[beej]

How is it that simply because one member of the Supreme Court (albeit the Chief Justice) called the mandate penalty a tax it is a tax? This despite that 4 others identified the penalty as an approapriate exercise of the Commerce Clause and the remaining 4 simply said the enitre act is unconstitutional.

Yes, the CJ is first among equals but his vote does not carry any more weight than any other justice; or am I wrong here?