Other than a judge's decision during a court case, are there other
times when such legal 'clarification' takes place that is at least (if
not more) binding than precedents? In essence, I'm curious if legal
professionals have a mechanism for testing and improving new laws that
falls between the two extremes of "try it in court and find out" and
"start a petition to motivate a senator to introduce a bill to make a
new law"
True Precedents
A true precedent is one that arises from a decision of an appellate court on the merits on an issue necessarily decided to resolve the issue presented in an actual case or controversy.
A legal holding on an issue not necessarily decided to resolve the case or not actually presented by a case is called "dicta". The requirement that there be an actually case or controversy is sometimes described as a prohibition on providing "advisory opinions." Cases that are resolved on grounds other than the merits (e.g. as a sanction for failing to meet a filing deadline for a brief) do not have legal effect as precedents.
Also, there are two kinds of precedents. Binding precedents are from courts that have appellate review authority over the court making the ruling. Non-binding precedents are decisions from other courts (including trial court orders) which are persuasive and considered in resolving cases, but are not binding on the court addressing an issue.
Usually non-binding precedents are resorted to for questions of common law where the state in question does not have binding precedents. But, it can also be used to interpret statutes and court rules, where a statute or court rule almost identical to a local statute or court rule has been interpreted in another jurisdiction. In particular, interpretations of federal court rules by the federal courts are given great weight as non-binding precedents by state courts whose court rules are modeled upon and almost identical to federal court rules.
A binding precedent is not necessarily binding forever, even when it is not expressly overruled. Changes in statutory law, or later precedents on the same or similar issues, may implicitly repeal the effectiveness of a precedent as well. And, of course, precedents may be distinguished because the facts of the current case, while similar, differ in some material way from those in the precedent.
Certified Questions Of Law
One slight hitch in this system is that a federal court applying state law, for example, in a diversity of citizenship case, which is presented with a legal issue which the state courts have not resolved definitively (i.e. with a binding decision of the state's highest court), may "certify" the narrow unresolved legal question in the case to the state's highest court to resolve on the actual facts present in the federal case, but only as to that isolated issue rather than the case as a whole.
Declaratory Judgments and Cases Resolved On Alleged Or Agreed Facts
It is possible for there to be an actual case or controversy in what is called a "declaratory judgment action" filed in a trial court seeking a resolution of an ambiguous or unresolved legal issue prior to anyone incurring actual damages or harm for actually violating the law if it is given one of the possible meanings it could have. There must still be a bona fide dispute between people who imminently need to resolve the legal issue, however, even then.
Many countries allow for judicial or quasi-judicial review of the facial constitutionality of laws in the legislative process before they take effect, but this is not allowed at the federal level in the United States and only a few, if any, U.S. states have such a process.
The reason for an insistence of resolving only actual cases or controversies and only in cases involving people who have "standing" to do so because they have suffered an actual injury, is primarily to prevent precedents from being made in sham litigation between a party and someone who is nominally the opposing party but is actually acting in collusion with the primary party to create a favorable rule of law for future cases where there is an actual dispute.
In a similar vein, sometimes cases are appealed from a trial court decision based upon stipulated or alleged facts, rather than following a full evidentiary trial on the merits.
Attorney Generals' Opinions
There is another means of establishing something close to precedents that are only binding upon government officials, which is sometimes quite effective as government officials are the only people who have to resolve a particular legal issue and there may be no one with standing to challenge a legal interpretation in court.
At the federal level, this is done with a legal opinion from the U.S. Attorney General (actually, more specifically, the Office of Legal Counsel within the Department of Justice) that is binding on all federal government employees until a court rules otherwise.
At the state level, this is done with a legal opinion of the State Attorney General that is binding, at least, on all state government employees. In some states, an attorney general's opinion is also binding on local governments, in other states, a local government's lead attorney (e.g. a county attorney, district attorney, or municipal attorney) has that authority in addition to, or instead of, the state attorney general.
Regulations
Also, in areas of law where the government enforces the law (as opposed to "private law"), at federal, state and local levels in the U.S., the government can enact a "regulation" interpreting what a law means that has generally applicable legal force unless it actually contradicts a statute, usually after a notice and comment period mandated by an administrative procedures act and subject to judicial review by people who are unhappy with the language of the final regulation for specified reasons.
Individualized Opinions
In some areas of tax and regulatory law it is possible to obtain an advanced ruling particular to a specific case regarding its legality (for a fee). In tax law, this is called a "private letter ruling" and this estops the government from treating the person obtaining the ruling as violating the law if the transaction or action taken proceeds as described in the ruling and the statutory law has not changed since it was issued. It is a non-binding precedent for others.
Private Bills
Most legislative bodies have the authority to pass certain kinds of "private bills" which modify the law retroactively for the benefit of a particular individual or small group of individuals. Many private bills concern immigration status and historically all divorces were granted and all corporations were formed via private bills.
Historical Events
Sometimes, in areas where there is little or no litigation, perhaps because the issue is non-justiciable or nearly so, past practice is given the effect of precedent. Usually these involve issues of constitutional law or international law.
For example, past practice regarding when recess appointments of the President were made was treated as a precedent when determining when a recess appointment is valid.
Similarly, the U.S. Civil War is considered a precedent by some legal scholars regarding the constitutionality of succession of a state from the United States without permission of Congress (at least).
Especially Authoritative Legal Commentary
Some statutes are adopted with official commentaries (usually uniform or model acts proposed by the Commission on Uniform State Laws) that are given the effect of precedents.
Also, a series of highly respected academic texts called the "Restatements of the Law" of various kinds of law (e.g. Contract, Torts, Judgments) which are published by a group affiliated with the American Bar Association with a highly respected process, are frequently given the effect of common precedents or majority rules of U.S. common law jurisdictions, by U.S. Courts in cases where the state in question does not have a precedent in place already regarding an issue addressed by the Restatement.
Opinions expressed in certain renowned academic treatises that are the leading comprehensive academic statements of the law in a field are also often treated as almost equivalent to a precedent. Likewise, a handful of famous legal treatises in effect at the time of the formation of the United States (i.e. 1776 or 1789 when the constitution was adopted) are often treated as authoritative statements of the state of the law at that time which has relevance as a precedent.