A judge has issued a stinging opinion recommending that the California Public Utilities Commission reject AT&T’s request to end landline service in California—a move that would leave thousands of West Marin customers without reliable service.

“It’s not clear why AT&T filed this application under existing rules and then attempted to convince the commission that it should ignore its rules based on flawed and erroneous assertions regarding the law and regulatory policy,” wrote Thomas J. Glegola,…