Sentence:  States <WSD>were</WSD> free to enact , within broad though ( perhaps ) determinate limits , their own rules as to the application of foreign law by their courts , to vary the law merchant , and to enact legislation with regard to many claims arising on the high seas . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)