Legal Question in Construction Law in California

It depends. If he associates other attorneys on some of his work, the name is not misleading. Many sole practitioners use contract attorneys as needed and could certainly use "and associates" in that case. There are limitations on stating you "specialize" if you are not, in fact, a specialist, but many attorneys are generalists who have some experience in a number of areas and are certainly qualified to practice in those areas of the law if they have or can acquire the requisite legal knowledge, either by research or by bringing in contract counsel. So unless he actually claims to be a specialist in all those fields AND is not, there is nothing wrong with advertising that he handles matters in all those areas of the law.

"Specializing in" does not necessarily mean "expert in." It may only mean that the lawyer prefers to take cases in those fields of law. Law is not quite the same as medicine when it comes to having, and advertising, expertise in a particular specialty. All lawyers are presumed (with a few rare exceptions such as patent law) to be competent and qualified to practice in any field of law, so if a solo practitioner advertises himself as specializing in, say, eight areas or fields of practice, it means, probably, that he will be more comfortable and experienced in those fields than in the other twenty or so fields.

Also, I question your conclusion that this lawyer is using a "non-existent company." Companies are of many kinds, including companies that engage in the practice of law. They range from sole proprietorship companies through partnerships and include corporations. This guy sounds like his company is a sole proprietorship, which does not prevent him from having employees or from dealing with other attorneys.

I would be the first to level criticism against another lawyer who was professing expertise where he had little or none, but "specializing in" does not quite equate with "expertise in" a particular field.......it just defines what the guy usually does, excluding other legal topics.