While most Americans support the principle of labor unionism, they are increasingly opposed to the right of public employes to strike.

Specifically, 59 percent of the public approve of labor unions, while about half this many, 31 percent, disapprove. However:

A 61 percent majority thinks policemen should not be allowed to strike, an increase of 9 percentage points since 1975.

62 percent would not allow firemen to strike - a 7-percentage-point increase since 1975.

51 percent say teachers should not be permitted to strike, a marginal increase in this sentiment (3 percentage points) since 1975.

A recent 18-notion survey conducted by Gallup International Research Institutes shows 54 percent of Americans predicting that 1978 will be a year of industrial disputes and strikes, whereas 23 percent take the opposite view.

The public's current endorsement of trade unionsim is down from the levels recorded in the period 1936 through the 1960s, but is the same as the figure recorded in the most recent previous survey, in 1973, when 59 percent also approved.

Following are the questions asked in the survey and trend comparisons of the national results and the findings by members of union and non-union families.

"Should policemen (for firemen or teachers) be permitted to strike, or not?"