"Ladies and gentleman, welcome to Air Berlin flight AB 9909, destination: this tarmac. Our flight has been cancelled as the pilot phoned in sick." Passengers of the embattled German airline had to endure the frustration of rerouted and cancelled flights when a large group of pilots called in sick. The impact of the collective action was drastic with reportedly around 100 flights cancelled. The pilot sick-out is a bargaining strategy in an industry known for sophisticated collective bargaining and trade union relations. American Airlines (1999), BahamaAir and Caribbean Airlines (2014) are some of the airlines reporting pilots booking off-duty due to reported illness en masse. But with strike action legal in most jurisdictions, why would employees book off sick rather than merely down tools and go on strike?

Many countries recognise and protect the right to strike. As the old adage goes, collective bargaining without the right to strike becomes collective begging. But there are usually substantive and procedural limitations on the right to strike. The International Labour Organisation (ILO) recognises various prerequisites for lawful strike action. In relation to fair procedure, these include prior notice of the intended action and conciliation or mediation before striking. In relation to substantive limitations, the ILO agrees for instance that employees cannot strike where they provide essential services.

The South African Labour Relations Act sets out procedural and substantive limitations on the right to strike in South Africa. It echoes various recommendations by the ILO, including requiring the trade union to declare a dispute with the employment tribunal, conciliation of the dispute and providing prior notice of the strike. The right is further limited in that employees may not strike where they agreed, in a collective bargaining agreement, that they will not strike on the issues covered in the agreement - e.g. wages for that year; they are bound by an agreement where they agreed to refer the issue in dispute to arbitration; and they may refer the issue in dispute to the Labour Court or employment tribunal for adjudication.

Employees may feel that the limitations in their right to strike make it ineffective for them to comply with the legal framework. The sick-out may thus appeal to them as a mechanism to get their employer over a barrel without jumping through statutory hoops, without either action sounding like a circus act. Calling in sick does not require the preceding legal process intended to orderly manage industrial disputes. It is immediate and, as many airlines can attest, bluntly effective. Of course, it does not detract form the relative attractiveness of this tactic that employees off sick are not docked a day's salary whereas going on strike means no pay for the day on which the employees did not work.

Does this mean that employers are at the mercy of employees when it comes to a sick-out? Employers willing to deal with employees who take part in such action may find that the law provides just the medicine for such an ailment.

Employees are not entitled to abuse sick leave. The legislature or employer provides for special leave due to illness or injury in order to allow staff to recuperate, convalesce and return to work when fit to resume duty. The employer's permission is typically not required for taking sick leave but there are normally rules regarding proof of illness in certain cases. Where the employee adheres to these rules he or she is typically entitled to be remunerated for period of absence. However, this does not mean that employees may try to deceive their employer about the true reason for their absence.

Dishonest conduct is detrimental to a continued employment relationship across the globe. Employees who lie to their employer should not expect sympathy from any forum when harsh action is taken against them. So, what can employers do when faced with a sick-out?

Employers should investigate the facts pertaining to each employee who called in sick. Within the bounds of the law applicable, employees should be required to confirm the circumstances of their inability to report for duty. In South Africa, an employer may decide to test an employee's alleged illness in a disciplinary inquiry. The employer may feel that it can prove, on a balance of probabilities, that the employee was not legitimately off ill but instead participated in unprotected industrial action. Factors that could suggest that this was the case include a demand on a matter of mutual interest by the employee group or trade union; the timing of the call by the employee; medical reports issued to a number of employees by the same medical practitioner; and other factors suggesting that the illness was a rouse (social media photos of the employee fishing while supposedly ill, or reports by other employees of the sick staffer gallivanting while reportedly recuperating).

A medical certificate, on its own, is not insurmountable proof of illness. The Labour Court has accepted that such a document is documentary evidence that may require testimony by the author (the medical practitioner). If the employer challenges the validity of the sick note, the employee may have to call the doctor to testify at the inquiry to prove that the certificate was issued by the practitioner, and that the doctor issued the certificate after examining the employee and concluded that the employee is too ill to report for duty. Absent confirmation, an employer could conclude that, considering the probabilities, the factors suggesting illegal strike action outweigh those proposing legitimate use of sick leave.

Dealing decisively with disgruntled staff who abuse sick leave may be just what the doctor ordered.