When an executive approves legislation, a written statement is sometimes issued alongside the signature. What that document does depends on which of several purposes it serves.
Most statements are ceremonial
The majority describe the law's purpose, credit its sponsors and explain why the executive supports it, which serves communication and nothing more.
These carry no legal weight and are functionally a press release attached to a formal act.
They are also the most common type by a wide margin, which is worth remembering when the practice is described as inherently controversial.
Interpretive statements direct the agencies
A second type instructs the executive branch on how an ambiguous provision should be read while implementing it.
Since agencies answer to the executive, that instruction has practical effect immediately, whatever a court might later conclude about the provision's meaning.
This is defensible where the text is genuinely ambiguous and someone must decide, and contested where the interpretation departs from what the legislature evidently intended.
Constitutional objections are the contested category
A third type states that a specific provision is unconstitutional and will not be enforced as written, while the executive nonetheless signs the bill.
Supporters argue the executive takes an oath to the constitution and cannot enforce a provision it believes violates it, particularly in a large omnibus bill.
Critics argue the available remedy is a veto, and that signing while declining to enforce takes the benefits of the bill without accepting its terms.
Courts give them limited weight
Judges interpreting a statute look primarily at its text and at the legislative record, and an executive statement is not part of what the legislature enacted.
Some opinions have referenced them as evidence of contemporaneous understanding, but no court treats them as controlling.
Litigation over an unenforced provision also requires someone with standing to bring it, and where the affected parties are diffuse, no case may ever be filed at all.
The practical significance is administrative
Because most laws are never litigated, the executive's interpretation is often the only one that is ever applied to a given provision.
That makes the statement consequential in practice even where its legal status is weak, since implementation is what most people encounter.
Legislatures respond by drafting more precisely and by attaching reporting requirements, which force the executive to state on the record how a provision is being applied.