Attempts to clamp down on free speech online aren't just limited to public social network posts.

Tanzania has charged five men with insulting President John Magufuli on social networks, one of whom (lecturer Dennis Mtegwa) is accused of offending the country's leader in a WhatsApp discussion group.

The other four have also been charged with using Facebook and WhatsApp posts to turn people against the police. All five have denied the charges and are currently free on bail.

The five men are the latest to run afoul of a recently instituted cybercrime law meant to punish anyone posting "false, deceptive, misleading or inaccurate" content online. As with many such laws, though, the administration is mainly using the law as a pretext for stifling political dissent.

The man charged with disparaging the President on WhatsApp was only questioning Magufuli's treatment of the political opposition as "an enemy" -- there's nothing to suggest that he was posting insults or lies. The other men, meanwhile, were only criticizing the police for focusing more on the opposition than on actual crimes.

There is mounting pressure to change the law. A US government aid agency, the Millennium Challenge Corporation, cancelled a $500 million funding package on the grounds that the law is "inconsistent" with its criteria.

That's unfortunate for regular Tanzanians who might benefit from the money, but the financial incentive might be what it takes to strike down a measure creating a chilling effect on freedom of expression.