The short answer is yes, but they should do so carefully. You can let someone go when they are on leave, or when they return, but you cannot let them go because they took a leave.
Employers have a duty to keep an employee’s job protected while they are on leave. In reality though this can be challenging to do, especially as business needs change and evolve. An employer may simply no longer have the need for someone in that role, or what happens frequently is they may find a temporary employee as a replacement who ends up out-performing the original employee, and they would rather make a switch of sorts. That second example would be offside, because the individual would not have lost their job if they didn’t take a leave.
The reality though is that employees may still be in a precarious position as they return from a leave, and terminating them immediately may quickly invite a wrongful dismissal claim, with allegations of discrimination included. For example, if a new father was terminated from his job the week that he returned from parental leave, it would be difficult not to draw the conclusion that he was penalized for being a parent.
Employers should speak with their trusted employment lawyer before making any termination decisions. We can help assess each individual situation, and find the ideal time to allow you to make your necessary business decisions.