"tough rules" is a correct and usable phrase in written English.
For example, you could use it in a sentence like this: "Workers in this company are expected to abide by tough rules."
Germany wants tough rules?
Therefore, tough rules have been applied on gasoline specifications.
In floor debate, Mrs. Lincoln defended her tough rules.
They believe that sheriffs in tough towns need tough rules.
Wall Street tried to beat back regulators' efforts to write tough rules after the legislation's lead.
On the campaign trail, President Obama took credit for imposing tough rules on Wall Street.
But jurisdictions with tough rules are undermined by neighbours with weak ones.
This past week the union's parliament passed tough rules for expelling and detaining them.
But without a public plan, tough rules and restrictions on insurance companies will be essential.
Schulmeyer set clear but tough rules about how decisions would be made.
However, if the Fed institutes tough rules for foreign banks, he said "retribution" by European regulators was possible.
