California Code, Health and Safety Code - HSC § 43150

The Legislature finds and declares that the people of this state, in order to achieve the purposes of this part, have a special interest in assuring that only those new motor vehicles and new motor vehicle engines which meet this state's stringent emission standards and test procedures, and which have been certified pursuant to this chapter, are used or registered in this state. The Legislature also finds and declares that this special interest must be protected in a manner which will not unduly or unreasonably infringe upon the right of the people of this state and other states to travel and do business interstate.