Legal Question in Constitutional Law in Oklahoma

Re: At what point can a proposed law be challenged in court?

Your question is posted as being about Oklahhoma law, but this is a federal issue and the answer is the same all over the country.

A law "proposed by the United States Senate" would, if enacted, become a federal law. Federal laws can only be challenged in federal courts, as no state has the authority to strike down a federal law.

Federal courts will not act where there is no actual controversy between the parties. Part of this requirement is that the plaintiff be able to show that he has been injured by the actions of the defendant. A bill being considered by the senate has not injured anybody yet. Because many bills are never enacted into law at all, there is a great chance that this bill never will injure anyone, and so the courts will not consider the type of suit you propose. Further, the language of most bills is revised several times before they are signed into law, and a challenge to a preliminary version is pretty pointless.

Even once the law is enacted, not just anyone can sue. The requirements you would have to meet will vary depending upon the nature of the challenged law, but at the very least you must await the President's signature or a congressional override of the veto.