There is actually very little room for interpretation of the rule here. The intent is clear. The rule is straightforward and is worded with precision. It spells out what is necessary and sufficient to demarcate the right from the wrong.
804.05 Disqualification and Suspension
A. A player shall be disqualified by the director for meeting any of the necessary conditions of disqualification as set forth in the rules, or for an of the following:
(4) Activities which are in violation of the law or park regulation or disc golf course rule, including the illegal consumption of drugs or alcohol.
A player shall be disqualified... does not say may be or could be but shall be as in make it so. Activities in violation of rules, whether that be the law of the land, the rules and regulations of the parks department, or the rules of the disc golf course shall result in disqualification.
What can cause a disqualification from a PDGA tournament?
Activities which are in violation of the law.
Activities which are in violation of park regulation.
Activities which are in violation of disc golf course rules.
And also, the illegal consumption of drugs or alcohol.
Even the thickest of molasses headed intellects have a knowledge about many laws and a general idea about many others. No one needs legal training to know that it is a violation of the law to assault someone, to steal their car, to rape their woman, etc… I happen to believe that most everyone in the United States knows that it is a violation of the law to consume illegal drugs and that most everyone knows what are considered to be illegal drugs. Consumption of marijuana, crack, meth, heroin, cocaine, opium and other controlled substances is in violation of the law (state and federal and sometimes county or city as well). There are specific formal and documented exemptions of the law. A person is not exempted from the law because they disagree with it. I hope no one has smoked themselves silly enough to forget that it is not legal for you to do so. This rule is clear. An activity which is in violation of the law, as in the law of the land inclusive and comprehensive, will result in disqualification. That is the rule. And guess what, this rule even specifically calls out illegal consumption. So if you do not know what is a violation of the law they have spelled out one specific example in the rules quite clearly.
Activities which are in violation of park regulation. Individual parks (city / county / state / national) have rules and regulations. Many times they are posted clearly on the premises. They are always available from the parks department. There are some activities which are not a violation of the law which may be a violation of park regulation. Guess what? Almost every park rules and regulations list explicitly and clearly spells out that it is not legal to consume controlled substances. Illegal consumption is a violation of the law and it is a violation of park regulations. Two for two here.
Activities which are in violation of disc golf course rule. Some disc golf courses have additional rules and regulations. An example might be a no smoking policy. Perhaps not an activity in violation of the law, or of park rules and regulations, but may be against the course rules. Violate the local course rules and you are disqualified.
Finally, the illegal consumption of drugs or alcohol. Illegal consumption = disqualification. If you are a fucking idiot and you did not know that the consumption of illegal substances was against city / county / state / federal law and you did not know that it is a violation of the rules and regulations of the parks department, then it is abundantly and super clear here. Illegal consumption. Disqualification.
What constitutes illegal consumption? If you personally have a formal exception from a law then you are not guilty of illegal consumption. You are however, in violation of other PDGA rules if your legal consumption of drugs or alcohol occurs during the round. So even if you have permission from God, consumption of drugs or alcohol during a round of PDGA play = disqualification.
Do not be an idiot. You cannot justify the rule away. You should not disregard it. It is clear follow it.
By the way, the context for this has been a PDGA rule which is applicable to PDGA tournament play. PDGA rules are not applicable for other events and occasions. However, the law is always applicable, even when you do not know it.