If signing up for this lawyers’ syndicate is something to which graduates from the law school are entitled, whether they are working or not, there is nothing wrong with your wife signing up, paying the fees and benefiting from medical treatment and pensions. It does not matter that the laws in your country are man-made as you say, because what is given to the syndicate comes under the heading of the state sponsoring individuals and graduates and this sponsorship may be necessary in some cases.
See also the answer to question no. 75613 for information on the ruling on working as a lawyer.
May Allaah help us all to do that which He loves and which pleases Him.
And Allaah knows best.