The rapid rise of commercial kosher certification during the mid-to-late 20th century caused this approach to fall out of favor with Orthodox Jews by the 1980s.
[1] Individual non-Orthodox synagogues differ on their interpretation of when "kosher by ingredient" food is or is not acceptable.
[3] Some Jews may keep kosher by ingredient for much of the year, but are stricter during holidays such as Passover and prefer to use hechshered products during those times.
Jews who follow this approach at restaurants may inquire about the ingredients in a dish, or mention lactose intolerance or shellfish allergies, rather than explain in detail the laws of kashrut to the server.
Ingredients that could render beer non-kosher include uncharacterized yeasts, extracts of hops and malts, and certain clarifying agents, among others.