A participial phrase contains a participle, which is a verbal form with the endings -ed or -ing (or irregular, such as "written", as in "Written on monday (the piece was famous already on Tuesday)). here the participle is "noted" and the whole phrase is this one:
YES the Puerto Rican law violated the dormant commerce clause. Puerto Rico does not have the power to regulate the cement labels because this law concerns commerce (and the US has the power to regulate commerce within the US territories and abroad).
