The law is not just the law.
There is the law and the intent behind that law.
Laws are made for specific purposes and with a specific intention in mind. Whether or not a law serves its specific purposes and whether or not it serves that intention are wholly dependant on its wording. If the wording is insufficiently clear as to the intent behind its purpose it can never be properly understood or interpreted by legal officers and scholars. If the wording leaves insufficient room for those legal professionals to apply it properly in all circumstances the law can never be effective.
For example, if a law is made against drunk driving, then that is the intent and purpose behind that law. If that law however is worded in such a fashion that it provides both minimum and maximum penalties, there is no room for the judge to do his work properly as a legal professional, because metaphorically speaking, his hands are tied. The law does not allow for cases that do not fit the intent behind it but do fit the criteria for the purpose that it was made to serve. A person whose (non-alcoholic) drink was spiked with GHB and who causes an accident for example would legally be guilty of drunk driving, but would not be responsible for his own actions. However, because of the way the law is worded, the judge would still either have to sanction him with the minimum sentence or find him not guilty. Of course, this example is wholly exaggerated, but hopefully it explains the dangers of strict liability laws and the concept of minimum sentences in legislation.