Head restraints were optional equipment until January 1, 1969, when their installation became mandatory under federal law.

Racial segregation in education became mandatory under the Act.

The first type is mandatory under the United States Constitution.

Residents put out the recyclable materials in a voluntary program that becomes mandatory under a city law going into effect today.

Such inspections became mandatory under state regulation in 1820.

So far it has taken the position that these other sanctions are not mandatory under the law.

Some companies, especially the larger ones, have already made many changes that will become mandatory under the new rules.

Participation in the small order execution system, which had been voluntary, will now be mandatory under the new guidelines.

Registration is mandatory under the constitution and the law of associations.

But as you know, this is not mandatory under the directive.