In an academic paper or book, one can quote a source "as quoted in" another source, when direct access to the main source is not available or not convenient. This could include parts of a court opinion quoted in other (more recent) opinions, or quotes in other sources, such as books or even news articles about the subject. If need be, such quotes can be verified by using offline sources to check the text of the original decision.
Court opinions/decisions often use "internal quotes" -- that is, they quote other opinions which in turn quote yet others, so if judges do this there seems no reason why a litigant cannot.
It is a little unusual to be quoting case law much at the municipal court level in a civil case, but if the quote is relevant, it may be used. It might be a good idea to identify the secondary source of the quote. Something like; "As quoted in X vs Y, the classic case of C vs D included the important statement that ...". The point is to let the judge know that your point has case law behind it. The judge will be able to verify the quote if s/he chooses. Online versions of court cases often include the official page numbers. If these are available, cite them, as they would help a judge find the quote in the more recent case which you are using to quote the older case.
If the older decision is one quoted favorably in many recent decisions, that can emphasize its importance and acceptance, with something like "In the classic case of C vs D, as quoted in X vs Y, Q vs R, and G vs H, as well as many other recent cases, Justice Bright said ..."