A restriction on where you work next is judged by how narrow it is

The starting position is against the clause

Post-termination restrictions sit awkwardly in most legal systems, because they restrain someone from earning a living in their own field. That tension shapes everything about how they are treated. In many jurisdictions such clauses begin from a presumption that they are unenforceable, and become enforceable only if the party relying on them can justify them.

Some systems go further and impose conditions of their own — a maximum duration, a requirement that the former employer pay compensation during the restricted period, or a rule that certain roles cannot be restricted at all. Others leave it almost entirely to the courts. The variation here is unusually wide even by the standards of employment law.

What is being protected, and what is not

Where restrictions are permitted, the justification is usually the protection of something identifiable: confidential information, trade secrets, customer connections, or the stability of a workforce. Those are treated as legitimate interests. Protection from competition as such generally is not, because ordinary competition is exactly what the system is trying to preserve.

That distinction explains most outcomes. A clause aimed at preventing a departing employee from taking the relationships they were paid to build has something to protect. A clause preventing them from working anywhere in the industry protects nothing in particular and looks like an attempt to remove a competitor, which tends not to survive scrutiny.

Breadth is measured in three dimensions

Restrictions are usually assessed on activity, geography and duration, and a clause can be too wide on any one of them. Activity means what the person is prevented from doing: a clause covering the whole of a business the employee had nothing to do with is vulnerable. Geography means where: a nationwide restriction on someone who worked with local customers is hard to justify.

Duration means how long the protection is genuinely needed, which usually relates to how quickly the protected information goes stale or the customer relationship can be rebuilt by a successor. Longer is not safer for the employer. A clause that overreaches on any dimension can fail entirely in some systems, since not every jurisdiction allows a court to trim an excessive clause down to something reasonable.

Clauses aimed at customers and colleagues sit between the extremes and are often more defensible than a broad prohibition on competing. A restriction preventing a departing employee from approaching customers they personally dealt with is narrowly aimed at a real interest. One preventing them from dealing with any customer of the business, including people they never met, is wider and correspondingly more vulnerable. Restrictions on recruiting former colleagues are assessed on similar lines, and are frequently the part an employer cares about most.

Confidentiality is a separate and more durable obligation

It is worth separating restrictions from confidentiality, because they are often confused and they behave differently. Genuine confidential information and trade secrets are usually protected in most systems independently of any clause, and that protection can continue indefinitely for information that remains secret.

What is not protected, generally, is the skill and general knowledge someone acquired doing the job. A person is entitled to take their competence with them. Drawing the line between an employer’s confidential information and an employee’s accumulated expertise is one of the genuinely hard questions in this area, and it is decided on facts rather than on drafting.

What happens in practice

Most restrictions are never tested, which distorts perception in both directions. Employers rely on the deterrent effect of a clause that might not survive a challenge, and employees frequently comply with restrictions that would have been unenforceable. Neither party usually wants the cost and delay of finding out.

When they are enforced, it often happens quickly and through urgent applications, because the value of the restriction disappears if the argument takes a year. That pace is worth understanding: a dispute of this kind can move from a letter to a court hearing in a very short time, which leaves little room for anyone to gather their thoughts afterwards.

Why you cannot tell by reading it

The most useful thing to know about a restriction is that its enforceability cannot be assessed from the wording alone. It depends on the role, on what the person actually knew and did, on the interests being protected, and on the law of the jurisdiction whose courts would hear it — which may not be the jurisdiction where the person lives.

This article describes the framework rather than any particular rule, and the rules are local, contested and subject to legislative change in several countries. If you are bound by a restriction and considering a move, or if you are drafting one, take advice from a qualified lawyer in the relevant jurisdiction before acting. Do it early, because in this area events tend to move faster than legal deadlines usually allow.