Noun: The happening took place yesterday.
Adjective: This is a pretty happening party.
Verb: I can't believe this is happening!
The latter can mark verbs and adjectives:
Verb: I stained the glass with paint.
Adjective: Stained glass adorned the church.
I'll focus on ambiguity with -ed in this post. These ambiguities arise in circumstances that tolerate both verbs and adjectives, such as (1) in predicate position following a form of the verb be, and (2) in certain post-nominal (i.e. following the noun) restrictive phrases. For example:
(1) The glass was stained.
(2) I missed the building obscured by the truck.
It's actually more complicated than a verb/adjective distinction (see this paper by Angelika Kratzer, for instance), but we'll keep things simple and refer just to this distinction. This situation can cause problems because it can lead to textual ambiguities between a reading more focused on an event and a reading more focused on a state.
For example, territories occupied in the recent conflict can refer to those territories that were seized during the recent conflict (the more event-focused reading), or to the territories that were in the state of being occupied for the duration of the recent conflict. Suppose a country occupied a bunch of territory in 1948, and then in a conflict in 1967 occupied a bunch more territories. Then a resolution requiring the country's armed forces from "territories occupied in the recent conflict" is ambiguous between a requirement to leave the 1967-occupied territories and a requirement to leave both the 1948- and 1967-occupied territories.
As you may have guessed, this is not strictly a hypothetical. The text is from United Nations Security Council Resolution 242, passed in November 1967, a few months after the conflict between Israel and the Arab states. I'm dealing with this text as my proposed note topic, but I'm treating a different issue: the controversial question of whether "territories occupied in the recent conflict" is universally or existentially quantified. But a friend of mine, who I'll call "Mr. S"*, pointed out this static/dynamic ambiguity, which I hadn't previously noticed.
Another non-hypothetical is the following text: "Any claim arising in respect of... the detention of any goods or merchandise by any officer of customs...." The case is Kosak v. United States, 465 U.S. 848 (1984), and the controversy is whether the text, which immunizes the United States from tort suits for claims that it describes, describes only claims arising from the act of detention, i.e. the seizure of the goods or merchandise, or whether it also covers claims arising from the state of detention, e.g. damage sustained while the goods or merchandise are in the government's storage warehouses. At least, I think that's what the dispute is - it's kind of hard to understand, and both Justice Marshall's majority opinion and Justice Stevens' dissents focus on the words arising in respect of rather than detention.
It has been suggested that there should be canons of drafting legislation to parallel canons of interpretation. Here's my prescription for drafters: Mind your Eds and your Ings! Or for the more formally inclined: Mind your participles and your gerunds!
* His real name is Brian Polis