It is common practice for public services to mount in-house bids when offering contracts for public competition.

ECONOMIST: Letters

In Belgium, it is common practice for police not to comment on ongoing investigations which may be why the attack was not reported until now.

BBC: Nicholas Mockford: Belgian police hunt killers

It is common practice for large companies in Japan to list their subsidiaries on the stock market, while maintaining a controlling stake thereafter.

FORBES: Do Inefficient Stock Markets Drive Bad Corporate Governance?

Then we generalized this instance, made it sound as though this is common practice and published the information to all of your readers.

FORBES: Magazine Article

Impersonating someone else to obtain phone records is generally illegal in California, where HP is based, though it's common practice for licensed investigators who are assigned to, say, chase down a fugitive from the law.

FORBES: Magazine Article